March 7, 2018

After just a handful of studies on the quality of romantic relationships among couples who practice consensual nonmonogamy (CNM), we now know enough that further research is “not imperative.” That is what researchers boldly claim in “Investigation of Consensually Nonmonogamous Relationships,” a study recently published in the prestigious journal Perspectives on Psychological Science. In more than 30 years of reading empirical studies, I have never seen scholars write that a research question has been sufficiently studied, even in areas with hundreds of published studies. But despite this being a relatively unexplored field, the science, they claim, is settled.

University of Michigan psychologist Terri Conley and colleagues compared consensual nonmonogamous romantic partners to their traditional monogamous counterparts. They concluded that those in CNM relationships do not differ from those in monogamous partnerships in reported levels of relationship satisfaction, commitment, love, and trust. Moreover, those in CNM relationships generally reported lower attitudes and behaviors regarding jealousy. The one exception was for “open relationships,” in which each partner pursue sex with others independently but without license to form emotional attachments to those outside the primary relationship. Other CNM types described in the study included “polyamorous relationships” (where primary partners mutually agree to have close emotional, romantic, and sexual relationships with more than one person, usually communicating openly and extensively about these relationships), as well as “swinger relationships,” in which primary partners consensually engage in one-time sex with others, usually at swinger parties. The study did not address “monogamish” marriages in which spouses aim for monogamy but accept occasional, dabbling flings.

Conley’s study has serious weaknesses that should limit our confidence in its findings, to say nothing of its more fanciful claims. First, the researchers do not inform readers what proportion of their participants were married — as opposed to being in some other form of committed relationship — nor do they break down their findings by marital status. In fact, the words “marriage” or “marital” are only substantively mentioned five times in this in this (extraordinarily lengthy) 28-page article, and that included references to “same-sex marriage” and “marriage equality.” Curiously, the words “parent” and “children” were each mentioned only once.

These oversights severely limit the study’s value and should, at the very least, invite skepticism about its conclusions. Among married participants, there are likely significant differences between monogamous and CNM individuals in terms of relationship quality, as monogamy is a strong norm and stigma about CNM relationships remains high. Intentionally or not, the researchers do not provide these straightforward analyses. Any claim that CNM and traditional monogamous relationships are equivalent that fails to look specifically at married couples or the effects on children is is severely limited.

Conley’s study also suffered from a weak sample: Nearly 90 percent of its participants were recruited from websites such as, with the remainder coming from undergraduates who posted information on social media. This self-selecting sample is representative of neither of those in CNM relationships nor of the public at large. Further complicating matters, two-thirds of the sample was female and more than 80 percent was White European.

Though the authors acknowledge that research on the quality of CNM relationships is imperfect, they assert it is “not imperative” that further work be done. Moreover, they justify this unique stance not on the strength of their data, but by citing the recent debate on same-sex marriage:

[C]onvenience sampling is an effective way to reach members of stigmatized groups. Despite potential problems of convenience samples (most prominently, concerns about social desirability), this type of research has had tremendous significance for the lives of marginalized groups. For example, social science research was cited in the monumental Obergefell v. Hodges marriage equality case and in related lower court rulings as well … despite the fact that much of the research cited relied on self-report measures and nonrepresentative samples. [… R]esearch indicating that LG [lesbian and gay] relationships are equivalent to heterosexual relationships, relying often on convenience samples and self-report, is accepted. That is, despite these methodological problems, we are aware of no calls for research that attempts to address this lacuna in the LG relationships literature or no conceptual pieces arguing that these relationships not be considered equivalent to heterosexual relationship until ample representative and non-self-report data have been gathered.

Translated, Conley and her colleagues argue that their study’s usefulness in assisting a “stigmatized” group — in this case, those in CNM relationships — is more important than the quality of their research. Put simply, social justice trumps science. (Also, who determines whether — and how – support for CNM relationships rises to the level of social justice that all progressives must accept?) Social science has a valuable and appropriate role to play in causes of social justice, but distorting or weakening its empirical value in support of a cause harms both science and justice.

Finally, the study’s findings must be viewed in a larger context. Over the last several decades, a large body of research has consistently found that infidelity is one of the most serious challenges to marital quality and stability, and two-thirds of Americans say they would not forgive a spouse for infidelity. Infidelity is one of the strongest predictors of divorce, dramatically increases its risk, and one of the most common reasons people give for a divorce. A host of psychological theories explain why infidelity can be so destructive to a relationship.

To be fair, Conley and her colleagues focused their efforts on individuals who reported being in consensual nonmonogamous relationships. Mutual consent may differentiate consensual sex outside of committed relationships from infidelity, but it is far from certain whether consent overcomes jealousy and other pressures. Additionally, “consent” needs to be unpacked: Just how mutual or enthusiastic does it need to be to matter? Since the study appears to contradict a large and established body of research, the appropriate scientific response should be to acknowledge its limitations and uncertainties and conduct more (and better) research to address the contradiction, rather than assert that society and science have sufficient answers to move on.

This overreach is particularly galling, given the public’s keen interest in the subject. In the immediate wake of the Conley study, the New York Times Magazine published a lengthy spread, titled “Is an Open Marriage a Happier Marriage?” The journalist’s answer can be summed-up by a quote from one of her subjects: “As our culture becomes more accepting of choices outside the norm, nonmonogamy will expand as an acceptable choice, and the world will have to change as a result.” A few months earlier, The Economist’s 1843 Magazine asked, “What’s Wrong with Infidelity?” In answer, the author quotes renowned psychotherapist Esther Perel, who questions why infidelity is the one sexual “indulgence that remains out of bounds” and muses that it remains so taboo because it is “the last [remaining] thing that defines a marriage.” Perel argues that infidelities should be viewed as natural, understandable imperfections or as forgivable lapses, rather than as traumatic events that signal deep flaws in the relationship and offending spouse.

There is no shortage of popular, sophisticated, avant-garde voices selling the merits of nonmonogamy for modern love and marriage. But those voices must be tempered by empirical research with strong methodology and humility in its conclusions.

About the Author

Alan J. Hawkins is the Camilla E. Kimball Endowed Professor of Family Life at Brigham University in Provo, Utah. His scholarship and outreach focuses on educational and policy interventions to help couples form and sustain healthy relationships and enduring marriages.

About our Editors