More people want open relationships, but many don't last. A sex researcher shares the 3 top reasons couples return to monogamy.

• Dr. Justin R. Garcia, head of the Kinsey Institute, said non-monogamy has gotten more popular.
• However, he said open relationships and polyamory tend not to work for most people.
• Some find non-monogamy to be too much work in practice.

Open relationships have gotten a cultural glow-up among younger adults. In practice, though, they're hard to pull off.

There's a lot of social media chatter where people in happy non-monogamous relationships report perks such as greater sexual satisfaction, multiple deep partnerships, and less restrictive love lives.

Still, outside the tweets, threads, and curated Instagram grids, the story is a bit more nuanced. A 2023 Pew Research report found that Americans are divided on open marriages. Of about 5,000 US adults surveyed, 37% found open marriages completely unacceptable. Younger generations approved more than anyone else: roughly half of 18- to 29-year-olds were accepting of open marriages.

Dr. Justin R. Garcia, the executive director of the Kinsey Institute, has also witnessed the growing popularity of non-monogamy in his work.

"People were talking about swinging in the 60s and 70s, but the language and the amount of attention to it changed, particularly over the last decade," Garcia told Business Insider, citing Amy C. Moors, a sexuality scientist who noticed a steady increase in people searching for terms related to polyamory between 2006 and 2015.

However, showing interest and actually engaging in the activity are two different things. In his new book, "The Intimate Animal," Garcia said that research from his lab at the Kinsey Institute, one of the most prominent research centers for human sexuality and relationships, found that one in five single adults in the US, out of about 8,700 studied, have had some kind of consensual, non-monogamous relationship at some point in their lives.

When looking at the past five years in another study of Garcia's, however, that number dropped significantly, suggesting that "more people try it than decide that it is a lifelong relationship structure for them," Garcia said. "In my social networks, that's been my experience as well."

It doesn't mean that they never work, he added. According to multiple studies, "while consensually open relationships might not work for everyone, or even for most people, there are many people for whom they do work perfectly well," he wrote in his book. Those in happy non-monogamous relationships, for example, don't fare psychologically or emotionally worse than content monogamous couples.

"In terms of who's a good candidate for it? My cheeky answer, but it's actually true, is those people who really want to do it," Garcia said. "It's similar to 'What's the right amount of sex that we should be having?' It's as much as you want."

Still, that doesn't mean open relationships work for everyone. Based on his research, Garcia shared the most common reasons non-monogamous partnerships don't work out.

It takes work to balance partners

One of the most common challenges to non-monogamous partnerships might be our own biology.

"We have such a fundamental, evolved drive to form intense pair bonds," Garcia said, ones that biologists theorize helped us thrive as a species over time. In his book, he said that "our brains don't appear particularly well-suited to processing intimacy with more than one partner at a time," be it another romantic partner or a sexual fling. Even fantasies of threesomes, Garcia said, more often involve an existing partner.

If romance is most often defined by sustained attention and effort, then it becomes more difficult when one or both partners have other people to focus on. Introducing a new partner into a shared home can cause friction with a spouse, as can skipping dinner with a spouse to spend it with another significant other.

Garcia said one of the "prevailing rationales" for consensual non-monogamy is having "too much love to give." However, he wrote, the opposite is true: "Most people don't have the biological, psychological, and social tools to love more than one person at a time."

Extra communication can be a turn-off

In his research, Garcia said the happiest non-monogamous couples have the same thing in common: "They tend to engage in a lot of communication."

One 20-person polycule, for instance, uses a software engineer strategy called "agile scrum" to resolve any relationship issues. It involves monthly reviews, discussion questions, and action points.

"Even casual polyamorous encounters take substantial effort and negotiation," Garcia wrote, including lots of communication. "Who needs more touch? Less? Who is feeling neglected? Who needs more time with whom? What is the state of things between each member of the polycule and each of the others?"

Some people find that level of frequent, in-depth communication builds their intimacy and brings them closer. Still, for many people, it's just too much work.

It can magnify issues instead of fixing them

In any healthy relationship, Garcia said there's a basic framework you have to follow: "There's me, there's you, and there's us." What might make one person happier, like having more romantic partners, might make the other feel neglected.

For a non-monogamous relationship to work, "you want to be able to both navigate your feelings of jealousy," Garcia said. Furthermore, he added, it helps if you actively enjoy knowing that your partner is with others.

The last reason you should be in a polyamorous or open relationship is because you want it to "fix" your current relationship. Often, he wrote, "the same issues that plague monogamous relationships — mismatched libidos, jealousy, boredom, and more — tend to surface in consensually non-monogamous ones." In fact, he added, they can multiply when partners aren't communicating or devoting enough time to each other.

"As one of my friends who had attempted to form a polycule once told me, 'It didn't work,'" Garcia wrote. "'I just pissed off two women instead of one.'"