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Open Relationships and Non-Monogamy: What the Research Shows
Love & Relationships
9 min read
One in five adults has been here. The research is more settled than the stigma suggests.
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Most cultural narratives about relationships assume monogamy as the default and treat any departure from it as either a failure or an experiment. The research takes a considerably less categorical view. Consensual non-monogamy - the umbrella term for relationship structures in which partners openly and mutually agree to outside romantic or sexual connections - is practised by a significant minority of adults, and the outcomes data does not show what the stigma predicts.
Consensual non-monogamy (CNM) is not a single structure. It is a category containing several distinct arrangements that differ in meaningful ways. The differences matter because conflating them produces confusion about what the research is actually measuring.
Open relationships typically refer to a committed primary partnership in which both people agree to pursue sexual (and sometimes romantic) connections outside the relationship. The primary relationship retains a distinct status; outside connections are usually bounded by agreed rules about disclosure, protection, frequency, or emotional involvement.
Polyamory describes the practice of having multiple emotionally and romantically intimate relationships simultaneously, with the knowledge and agreement of everyone involved. This is not the same as an open relationship: polyamory explicitly includes the possibility of deep emotional connection with multiple partners, not just sexual access. Hierarchical polyamory distinguishes between primary and secondary partners; non-hierarchical polyamory (sometimes called "egalitarian polyamory") does not apply that ranking.
Swinging refers specifically to recreational sexual activity outside a committed relationship, typically as a shared activity rather than separately. Swinging communities tend to maintain a strong distinction between sex and emotional connection with outside partners.
Relationship anarchy is a philosophical approach to relationships that rejects the notion of hierarchies between relationship types - rejecting the premise that romantic relationships are inherently more significant than friendships, or that any relationship structure is the default. It sits at the more ideological end of the spectrum.
These distinctions matter for research interpretation. A study that measures "non-monogamy" without specifying which type may be mixing populations with quite different experiences, and conclusions drawn about one form may not apply to others.
Non-monogamy is considerably more common than most people assume, particularly given how little it is discussed in mainstream culture. Haupert et al. (2017), publishing in the Journal of Sex and Marital Therapy, surveyed a US sample and found that approximately 21% of adults reported having engaged in consensual non-monogamy at some point in their lives. That is roughly one in five adults - a figure that makes CNM far from marginal.
The prevalence varies somewhat by demographic group. People who identify as LGBTQ+ report higher rates of CNM experience than heterosexual cisgender respondents. Younger adults report higher rates than older adults, which may reflect either generational change or the simple fact that younger adults have had fewer years in which to form long-term exclusive relationships. The Haupert et al. data also found no significant differences in reported rates across racial groups, educational levels, or political affiliations.
The discrepancy between the prevalence data and public awareness is likely explained by stigma. Conley et al. (2013), examining attitudes toward CNM in a series of studies, documented consistent stigma against people in non-monogamous relationships - including attributions of lower competence, trustworthiness, and relationship satisfaction - even when the relationships were described as consensual and long-term. People in CNM relationships frequently report not disclosing their relationship structure to family, colleagues, or medical providers because of anticipated negative reactions. This social invisibility makes the practice seem rarer than it is.
The central question most people want answered is: are people in open or polyamorous relationships more or less satisfied, happy, or stable than people in monogamous ones? The answer from the research is: not meaningfully different, when the non-monogamy is consensual.
Rubel and Bogaert (2015), in a meta-analysis published in the Archives of Sexual Behavior reviewing multiple studies comparing CNM and monogamous relationships, found no significant differences in relationship quality, relationship satisfaction, sexual satisfaction, love, trust, commitment, or jealousy management between the two groups. The outcomes were comparable when the non-monogamy was explicitly agreed upon by both partners.
This finding requires careful interpretation. It does not mean that opening a relationship will not affect it - clearly, the transition period involves real adjustments. It does not mean that all non-monogamous arrangements produce good outcomes - poorly negotiated or non-consensual arrangements predictably do not. What it says is that a well-functioning CNM relationship is not inherently less satisfying or stable than a well-functioning monogamous one.
Sexual satisfaction is worth noting separately. Several studies find that people in CNM relationships report relatively high sexual satisfaction compared with people in long-term exclusive relationships. This may reflect a genuine effect - novelty and variety are known contributors to sexual interest, and CNM structures allow for this in ways monogamy does not. It may also reflect a selection effect: people who seek out non-monogamous arrangements may be particularly invested in their sex lives and more likely to report high satisfaction as a baseline.
Jealousy does appear in CNM relationships. Studies do not find that CNM people are free from jealousy; rather, they tend to have developed more explicit tools for recognising and processing it. Research by Sheff and others in the polyamory literature suggests that CNM communities have built substantial informal knowledge around jealousy management - treating it as information to be examined rather than a command to be obeyed, and distinguishing between jealousy as an emotional response and jealousy as a behavioural directive.
The consistent finding across the CNM literature is that the quality of the outcome correlates strongly with the quality of the communication and negotiation that precedes and accompanies it. This is not surprising - it is the same finding as in most relationship research - but it applies with particular force to non-monogamous arrangements because there is no social script to fall back on.
Monogamous relationships can function in many cases on implicit assumptions, shared cultural norms, and unspoken expectations. Non-monogamous arrangements cannot. They require explicit negotiation of what is permitted, what is desired, what the communication expectations are (does a partner need to know about outside encounters? in how much detail?), what the boundaries are around particular people or situations, and how to revisit the agreement as circumstances change.
Compersion is a term that originated in polyamory communities and describes a specific emotional experience: positive feeling in response to a partner's happiness with someone else. It is roughly the opposite of jealousy - pleasure derived from a partner's pleasure, even when that pleasure involves someone outside the relationship. Compersion is not universal and is not a requirement for CNM relationships to function, but many people in established non-monogamous relationships describe experiencing it and point to it as one of the more unexpected rewards of the structure.
The practical prerequisites most practitioners and researchers identify: the ability to articulate needs and limits clearly, comfort with ongoing renegotiation as situations evolve, sufficient individual security that jealousy - which will arise - does not override the person's ability to communicate about it, and time management skills that account for the genuine logistical demands of maintaining multiple relationships.
Jealousy is real in CNM relationships and minimising it helps no one. The difference between CNM communities and mainstream relationship culture is not the absence of jealousy but a different approach to it. Jealousy in CNM contexts is frequently treated as a signal worth examining - what specifically triggered it? what need is it pointing to? what would need to be different for it to be less intense? - rather than as automatic evidence that the arrangement is failing.
Time and energy are finite. Maintaining multiple relationships - particularly multiple emotional relationships - takes real investment. This is one of the most commonly underestimated challenges for people new to polyamory: the romantic idealism about abundance of connection runs into the practical reality that each relationship requires attention, communication, and presence. People with demanding professional lives, children, or health issues sometimes find the overhead of multiple relationships is not compatible with those other demands.
Social stigma remains a practical challenge in most contexts. The Conley et al. (2013) research on CNM stigma documents that people in non-monogamous relationships face genuine social costs - in how they are perceived by family, how they navigate disclosure in medical contexts, how they are treated legally in some jurisdictions (particularly where multiple cohabiting partners are involved in parenting). The research documents this as an external problem rather than an internal one, but the external problem is real and worth accounting for.
On the reward side: research and self-report consistently point to several distinctive positive features of CNM relationships when they are functioning well. The communication skills required for CNM - explicit negotiation, regular check-ins, the ability to articulate desires and limits - tend to improve the quality of the primary relationship itself. The forced explicitness around what each person needs is something many monogamous couples never achieve. Several longitudinal accounts from people in long-term CNM relationships describe this transfer as one of the more underrated benefits: the relationship became more explicitly tended to, not less, because the CNM structure required it.
None of this constitutes an argument for or against any particular relationship structure. What the research does argue for is informed choice - understanding what the evidence actually shows before deciding what is right for a particular person and set of relationships, rather than accepting the cultural defaults uncritically in either direction.