There is no fixed scientific list of “relationship types”, and no relationship model is psychologically healthy simply because of its structure. Relationships can be described through different dimensions: exclusivity, sexual or romantic openness, number of partners, hierarchy and living arrangements. What matters is how agreements are built, whether consent is genuine and how the people involved experience the relationship.
Search for “types of relationships” and you may find lists of ten, fifteen or twenty categories: monogamous, open, polyamorous, throuple, LAT, swinging, relationship anarchy and more. The problem is that these labels do not all describe the same feature of a relationship. Some refer to sexual exclusivity, some to how many people are involved, some to living arrangements, and others to how agreements and priorities are organised.
That is why this guide will not try to force every relationship into a rigid box. Instead, we will build a map. This makes it easier to understand terms such as monogamous relationship, open relationship, polyamory, throuple or Living Apart Together (LAT) without assuming that one way of relating is automatically better than another.
We will also look at what research tells us about relationship satisfaction, consent, jealousy and communication, and what may happen when two people discover that they do not want the same relationship model.
What do we really mean by “types of relationships”?
Relationship psychology does not offer one universal classification with a set number of relationship types. Even widely used terms such as monogamy, open relationship and polyamory can describe very different agreements from one relationship to another.
It is also important to separate relationship structure from sexual orientation. A heterosexual, gay, lesbian or bisexual couple may be monogamous, open or involved in some form of consensual non-monogamy. Likewise, living together or living apart does not tell us whether a relationship is exclusive.
Rather than asking only “What type of relationship are you in?”, it can be more informative to ask: What have you agreed about exclusivity, other relationships, living arrangements, priorities, sexuality and boundaries?
A map for understanding relationships: five different dimensions
The same relationship can sit in several categories at once. For example, a couple may be monogamous, closed and LAT; another may be polyamorous, non-hierarchical and living together. Separating the dimensions makes the picture much clearer.
Exclusivity
Is there sexual exclusivity, romantic exclusivity, both, or neither? Even within monogamy, it helps to clarify what each person considers a breach of the agreement.
Openness
If outside experiences or relationships are allowed, are they sexual, romantic or both? Do they happen together, separately, occasionally or as ongoing relationships?
Number and configuration of relationships
There may be a dyad of two people, a three-person relationship, a quad, or a wider network in which not everyone has the same kind of relationship with one another.
Hierarchy or priority
Some arrangements explicitly distinguish primary and secondary relationships; others try not to assign a predetermined rank to one relationship over another.
Living arrangements
Living together, maintaining separate homes or having a long-distance relationship describes day-to-day organisation, not necessarily exclusivity.
Monogamous and closed relationships: similar, but not identical
Monogamous relationship
In a monogamous relationship, two people agree some form of exclusivity. In practice, that may mean sexual exclusivity, romantic exclusivity or both.
The word “monogamy” can sound straightforward until two people start defining what fidelity means to them. Does kissing someone else count? Sexting? Using dating apps? Developing a highly intimate emotional bond? Watching pornography? There is no single universal answer to all of these questions. The useful part is making sure both partners are not silently working from completely different definitions.
Closed relationship
In everyday language, a closed relationship usually describes an arrangement in which sexual or romantic relationships remain within the agreed relationship or group.
That means “closed” does not necessarily mean “two people”. A relationship involving three or more people may also agree exclusivity within the group. Here, we use “closed” as a practical description of an exclusivity agreement rather than a clinical category.
Consensual non-monogamy: a broad category, not one relationship model
Consensual non-monogamy, often shortened to CNM, refers broadly to relationships in which the people involved agree that certain sexual and/or romantic relationships or experiences with other people may occur.
Research commonly includes open relationships, swinging and polyamory under this broad umbrella. They are not interchangeable. They may differ in the role of romantic attachment, sexuality, living arrangements and the agreements people make.
The word consensual is crucial. Hangen, Crasta and Rogge examined non-monogamy using three dimensions: mutual consent, communication and comfort with the agreement. In their sample, monogamous and consensually non-monogamous groups with high levels of these features showed better functioning than partially open or one-sided arrangements.
An open relationship does not mean that “anything goes”. Trust can also be broken in a non-monogamous relationship when somebody deliberately hides relevant information or crosses an agreement that mattered to the people involved.
Open relationships, swinging and inviting a third person: what is the difference?
Open relationship
In an open relationship, the couple or partners allow certain outside encounters or relationships according to their own agreements. The openness may be mainly sexual or may include other forms of connection.
Swinging
Swinging generally centres on consensual sexual experiences, often involving other couples or shared sexual settings that have been agreed in advance.
Inviting a third person
Some couples choose to include a third person occasionally in shared sexual experiences. In Spanish-language sexology, the expression pareja permeable is sometimes used for this kind of arrangement. Our English guide focuses on the clearer description: inviting a third person into the relationship.
An important clarification
There is no standard psychological category called a “permeable relationship” in English. What matters clinically is not the label but the actual agreement: who is involved, what is allowed, whether both partners genuinely want it and what happens if someone becomes uncomfortable.
Two couples who both call their relationship “open” may live that agreement very differently. One may allow occasional sexual encounters but not seeing the same person again; another may allow ongoing relationships. One may prefer shared experiences; another may keep outside experiences separate. Again, the label does not replace the conversation.
Can opening a relationship rekindle desire?
Novelty may increase excitement, curiosity or anticipation for some people, but that does not make opening a relationship a treatment for an unhappy partnership. If the central difficulty is resentment, emotional disconnection, loss of trust or sexual pressure, adding other people can increase complexity without repairing what is already happening between the partners.
We have a dedicated guide planned for this question: can opening a relationship rekindle desire?
Polyamory, throuples, quads and other configurations
Polyamory
The American Psychological Association describes polyamory as the practice or orientation of maintaining multiple romantic and/or intimate relationships at the same time with the knowledge and informed consent of everyone involved. It sits within the broader category of consensual non-monogamy.
Polyamory therefore does not simply mean “having sex with several people”. It may involve more than one emotionally significant relationship, and those relationships can be organised in many different ways.
Throuple or three-person relationship
A throuple, sometimes described more neutrally as a triad or three-person relationship, is a relationship configuration involving three people. It should not be confused with a threesome: a one-off sexual experience between three people does not by itself create a three-person relationship.
Quad relationship
A quad is a configuration involving four people within a relationship network. It does not necessarily mean that all six possible one-to-one relationships between those four people are equally romantic, sexual or emotionally close.
Polycules and relationship networks
In polyamorous communities, the term polycule is sometimes used for a network of connected relationships. One person may have two partners who are not partners with each other, while those partners may have relationships of their own. The structure may look complicated from the outside, but psychologically many of the same themes remain: expectations, time, care, boundaries, safety and communication.
Hierarchy, non-hierarchy and relationship anarchy
Hierarchical and non-hierarchical polyamory
Some people explicitly describe one relationship as primary and others as secondary. Others try not to assign predetermined ranks to their relationships. These differences are discussed in polyamory research, including studies comparing relationship satisfaction and attachment security across hierarchical and non-hierarchical arrangements.
Our guide to hierarchical and non-hierarchical polyamory will look more closely at what it means to prioritise one relationship and what difficulties can arise when labels such as “primary” and “secondary” become rigid.
Relationship anarchy
Relationship anarchy challenges the assumption that relationships should automatically be organised according to socially predetermined hierarchies. It does not mean an absence of commitment, responsibility or boundaries. In fact, when fewer things are taken for granted, explicit conversations about needs and expectations can become even more important.
Living Apart Together (LAT): being together without living together
Living Apart Together (LAT) describes couples who consider themselves in an ongoing relationship while maintaining separate homes. It is a particularly useful example of why not all relationship labels describe the same dimension.
A LAT couple may be monogamous or non-monogamous, open or closed. “LAT” tells us where and how they live, not who they may form relationships with.
A 2024 study of LAT relationships in Spain found that motivations varied across life stages. For younger adults, living apart could be a stage before cohabitation shaped by work or housing circumstances; in midlife, it could be more closely linked with maintaining autonomy and previous family experiences.
Which type of relationship works best psychologically?
This is probably the most important question in the whole guide, and also one of the easiest to answer badly when relationship models are treated as competing ideologies.
A meta-analysis published in 2026 brought together 35 studies and 24,489 participants and found no overall significant differences in relationship satisfaction or sexual satisfaction between people in monogamous and non-monogamous relationships. The analyses also did not show consistent differences according to the specific non-monogamous arrangement studied.
This does not mean that “every model works equally well for everyone”. It means something more useful: relationship structure alone does not tell us who will have a satisfying relationship.
“From my clinical perspective, I am less interested in the label a couple uses than in whether the people involved can feel heard, safe and free within their agreements. A relationship is not more mature because it is open, nor more committed because it is monogamous.” — Héctor Lozano Jiménez
A relationship model may fit one person's values and needs very well and feel deeply uncomfortable to another. Difficulties arise when a structure is used to avoid a necessary conversation, to keep someone from leaving, or to prove that we are more “modern”, “free” or “committed” than somebody else.
If you want to look more closely at safety, reciprocity and respect, our guide to recognising a healthy relationship and our article on horizontal and vertical relationships may be useful next steps.
Agreements matter more than the label
Some couples use a very specific label but have never discussed what that label actually means to each person. Others do not know what to call their relationship but have clear, revisable agreements.
Research on consensual non-monogamy has highlighted practical relationship-maintenance themes such as talking about attraction to other people and jealousy, sexual health, the distribution of time and resources, hierarchy, shared sexual experiences and other agreements. These are not universal rules, but they show how much day-to-day management matters.
Six useful conversations
- Fidelity: what does it mean to us, and what experiences would we consider a breach of trust?
- Exclusivity: do we want sexual exclusivity, romantic exclusivity, both or neither?
- Consent: can either of us say “no” without fearing abandonment, punishment or guilt?
- Boundaries: what is within our agreement and what is outside it?
- Care: how will we talk about jealousy, sexual health, time, intimacy and emotional needs?
- Review: what will we do if somebody's needs change or an agreement no longer feels comfortable?
A conversation about agreements should not become a negotiation designed to wear the other person down until they accept something they do not want. Consent is not surrender. Agreeing to an experience once does not create an obligation to agree again.
Jealousy, infidelity and changing your mind: difficulties that can appear in any model
“If I feel jealous, does that mean this relationship model is wrong for me?”
Not necessarily. Jealousy can appear in monogamous and non-monogamous relationships. The emotion may point to fear of losing a relationship, comparison, insecurity, a need for attention, uncertainty or an experience that has crossed a personal boundary.
The goal should not be to prove that you are capable of “not feeling jealous”, but to understand what the emotion is telling you and what the relationship needs in order to respond to it. We have a dedicated guide planned for this situation: jealousy in an open relationship.
Can infidelity happen in an open relationship?
Yes. Infidelity is not defined only by sexual or romantic contact with somebody outside the relationship. Trust may also be broken when somebody deliberately crosses a meaningful agreement and hides it. An open relationship may have boundaries around particular people, sexual health, what information is shared, specific sexual practices, repeated encounters or romantic attachment.
What if I change my mind?
Relationship agreements need to be reviewable. Changing your mind does not guarantee that the people involved will find a compatible solution, but nobody should remain in a relationship structure they no longer consent to simply because “they said yes before”.
Two common difficulties deserve guides of their own: my partner wants an open relationship and I don't and we opened our relationship and now I regret it.
When the relationship model starts to cause distress
You do not need a perfect label for your relationship before asking for help. Couples therapy can support monogamous couples as well as couples or partners exploring other agreements, without treating one model as morally superior and while paying attention to the needs of the people involved.
It may be useful to stop and review what is happening when:
- one person accepts a relationship model because they are afraid the other person will leave;
- there is persistent pressure to open or close the relationship;
- agreements are repeatedly changed by one person alone;
- important information is hidden or trust has been repeatedly broken;
- jealousy or anxiety occupies a large part of everyday life;
- a third person is being used in an attempt to repair an earlier relationship crisis;
- there are major differences in values or needs and no genuinely compatible agreement has emerged;
- sexuality has become a persistent source of pressure, guilt or conflict.
Therapy should not decide whether a couple must be monogamous, open or polyamorous. It can help separate desire from pressure, clarify expectations, understand the fears that arise and explore whether there is an agreement that is genuinely compatible for the people involved.
When the difficulty centres particularly on desire, intimacy or sexual agreements, sex therapy for couples may also be worth considering. And if you want to examine cultural expectations about what love is “supposed” to look like, our article on Disney and romantic love myths offers a useful companion perspective.
Ocnos guides to relationship models
This article is the starting point for the cluster. Each guide explores one model or one common difficulty in greater depth and links back to this general map.
Frequently asked questions about relationship types
How many types of relationships are there?
There is no scientifically fixed number. Relationships can be described across several dimensions, including exclusivity, sexual or romantic openness, number of relationships, hierarchy, living arrangements and agreements. One relationship may therefore fit several descriptive categories at the same time.
What is the difference between an open relationship and polyamory?
An open relationship usually refers to a relationship that permits certain outside encounters or relationships according to agreed boundaries, often with a sexual emphasis. Polyamory allows for multiple romantic and/or intimate relationships with the knowledge and consent of everyone involved. In practice, there is considerable diversity within both terms.
Is a throuple the same as a threesome?
No. A threesome describes a sexual experience involving three people. A throuple or triad describes a relationship configuration involving three people and may include emotional bonds, commitment, living arrangements and its own relationship agreements.
Can infidelity happen in an open relationship?
Yes. Open relationships still have agreements. If somebody deliberately crosses a significant boundary or hides behaviour that was outside the agreement, trust can be broken even though relationships with other people are permitted in some circumstances.
Do open or polyamorous relationships work worse than monogamous relationships?
The available evidence does not support that conclusion. A 2026 meta-analysis of 35 studies and 24,489 participants found no overall significant differences in relationship or sexual satisfaction between monogamous and non-monogamous participants. That does not mean every model suits every person: compatibility, consent and the quality of agreements still matter.
Does jealousy mean an open relationship is not working?
Not necessarily. Jealousy can appear across different relationship models. It can be useful to explore what triggers it, what fear or need it may be signalling, and whether there is a difficulty involving agreements, security, comparison, time or trust.
What does Living Apart Together (LAT) mean?
Living Apart Together describes couples who consider themselves in an ongoing relationship while maintaining separate homes. It may be an active choice for autonomy or reflect work, housing, parenting, distance or other circumstances. LAT does not tell us whether the relationship is monogamous or non-monogamous.
Can couples therapy help us decide which relationship model we want?
Therapy can help people explore expectations, values, boundaries, fears and differences in desire, but its role is not to impose a relationship model. The aim is to support clearer conversations and explore whether an agreement can be both freely chosen and genuinely compatible for the people involved.
If the way you relate has become a source of conflict
You do not need to arrive in therapy with the perfect label. Sometimes the difficulty is precisely that one person wants more exclusivity, another wants more autonomy, or both have avoided talking about what they really want because they are afraid of what the conversation might mean.
At Ocnos Psychology Clinic in Palmones, we work with couples from Campo de Gibraltar, Gibraltar and nearby areas, and we also offer online appointments. We can help you understand the conflict, review agreements and make clearer decisions without assuming that there is only one correct relationship model.
Main sources consulted
For this guide, we have prioritised reviews, larger studies and institutional sources that directly support the article's main claims.
- Anderson JR, Hinton JDX, Bondarchuk-McLaughlin A, et al. Countering the Monogamy-Superiority Myth: A Meta-Analysis of the Differences in Relationship Satisfaction and Sexual Satisfaction as a Function of Relationship Orientation. Journal of Sex Research. 2026;63(1):130–142. PubMed.
- Scoats R, Campbell C. What do we know about consensual non-monogamy? Current Opinion in Psychology. 2022;48:101468. PubMed.
- Hangen F, Crasta D, Rogge RD. Delineating the Boundaries Between Nonmonogamy and Infidelity: Bringing Consent Back Into Definitions of Consensual Nonmonogamy With Latent Profile Analysis. Journal of Sex Research. 2020;57(4):438–457. PubMed.
- Nishikido M, Castro-Martín T. Living apart together in contemporary Spain: Diverse motivations across life stages. Advances in Life Course Research. 2024;61:100627. PubMed.
- American Psychological Association. APA Dictionary of Psychology: polyamory. APA Dictionary of Psychology.
Clinical note: this article is for general information and does not replace an individual or couples psychological assessment. Relationship labels describe agreements or configurations; they are not diagnoses. If there is violence, sexual coercion or fear of expressing boundaries, the priority is the safety of the person affected.
