Skip to main content

Verified by Psychology Today


Are Monogamous Relationships Really Better?

Science scrutinizes monogamy

In one way, the answer to the question in the title of this article, “Are monogamous relationships really better,” is obvious. If the criterion is, do people think they are better, then the answer is an overwhelming yes.

Being monogamous has a similar ideological sheen to getting married – it is something that we think we are supposed to do. Ask people why everyone should be monogamous/get married, and they will easily generate reasons for why it is better to do so than to be non-monogamous/ stay single.

I have done lots of studies of stereotypes of single people. Terri Conley and her colleagues have been studying stereotypes of people who have what they call “consensually non-mongamous” (CNM) relationships. We have each gone on to answer the next question: Are the stereotypes true, or are they mostly myths and prejudices?

I. First, some definitions.

Conley likes the CDC definition of monogamy: “mutual monogamy means that you agree to be sexually active with just one person, and that person has agreed to be sexually active only with you.”

Consensually non-monogamous relationships (CNM) are “relationships in which both partners have openly agreed that they and/or their partners will have other sexual or romantic partners.”

Polyamory involves “having consensual loving and romantic relationships with more than one partner.” That’s different from swinging or open relationships, in which the relationships may be just sexual and not necessarily loving or romantic.

II. My dog in this fight.

My dog is the one that isn’t keeping everyone awake and annoyed with its barking. I think contemporary American society has gotten carried away with its insistence that there is a right way to engage in sex (have lots of it, with just one person – or just one at a time). I think we should recognize that all sorts of approaches to sex (including asexuality and CNM) can be just fine for some people, and we should not keep trying to make everyone act and feel the same way. (This is not an endorsement of hurtful sex, of course.)

My other dog is science. If we (royal we) are going to proclaim that one kind of sex is best, then my answer to that is: Show me the data.

III. The research.

There is not all that much research on CNM. As Conley points out, scientists seem so sure that monogamy is best that they have not bothered to do all that much research on the matter. Conley and her colleagues now have an ongoing program of research, and they have also reviewed research from other labs. (Reference is at the end.)

Does monogamy provide “a life full of safe and excellent sex”?

That’s one of the assumptions about monogamy – that it brings all sorts of sexual benefits. But research shows that “sexual frequency, on average, decreases over the course of a (presumed monogamous) romantic relationship.” There is also evidence to suggest that sexual desire decreases over the course of a long-term romantic relationship.

As for how safe the sex is in monogamous vs. CNM relationships, the assumption is that monogamous sex is safer. The research disagrees. What seems to happen is that people assume there is more safety in their supposedly monogamous relationships than there is in fact. As Conley put it, “couples put condoms away, typically within the first couple months of dating, and switch to other forms of birth control when they feel comfortable with one another, rather than after objective testing for STIs.” (STIs are sexually transmitted infections.) In long-term relationships, including many marriages, partners often do not take into account the very real possibility of infidelity.

Here are more specifics of the research findings. (I’m taking a paragraph from the article and turning the sentences into bullet points, for ease of reading.)

  • “Sexually unfaithful individuals were less likely to use barriers during their extradyadic encounter, less likely to tell their partner about the encounter, and less likely to be tested for STIs than individuals in CNM relationships.”
  • “Sexually unfaithful individuals were less likely to use barrier methods in their primary relationship than CNM individuals.”
  • “People in ostensibly monogamous relationships were also more likely to make condom use mistakes.”
  • “Individuals often use condoms or other barrier methods more frequently with casual partners than with ‘regular’ partners.”

In a subsequent post or two, I will review what the Conley and her colleagues found about the answers to these questions:


Conley, T. D., Ziegler, A., Moors, A. C., Matsick, J. L., & Valentine, B. (2012). A critical examination of popular assumptions about the benefits and outcomes of monogamous relationships. Personality and Social Psychology Review.

[Notes. (1) Thanks to Rolf Degen for the heads-up about this article. (2) See below for some other recent blog posts.]

Do you feel judged for being single?

Why do so many Americans like big box stores and chain restaurants?

More from Bella DePaulo Ph.D.
More from Psychology Today