by JONATHAN KENDALL

From the glimmering blocks around Times Square to the sunbaked streets of the Hollywood Hills, open relationships seem to be everywhere nowadays, especially among Millennials. Indeed, a 2016 poll by YouGov.com suggested that nearly a fifth of Americans under the age of 30 have had some kind of sexual activity with someone else while their partner knew about it.

However, does opening up a relationship to new playmates strengthen the bond between a committed pair, or, does doing so compromise it? One of New York’s top dating coaches, Susan Winter, tells Big Think that open relationships, much like the wildflowers in Central Park, tend to wither over time. The reason? From the get-go one of the partners preferred monogamy. More than half of Millennials still believe that monogamy is the only way to go.

However, when their relationship—perhaps one that has lasted for several years—is at risk, the individual who prefers an exclusive relationship may “submit” to their partner’s request to be in an open relationship. What’s repressed in an effort to retain the relationship may become a thorn in a sweetheart’s side.

“Open relationships work better in theory than they do in real life. … Most often, I hear the term ‘open’ being thrust onto an unwilling partner by the partner who wants to cheat,” says Winter, recounting her experience counseling couples. “The decision to be open is not mutual. The partner who wants to cheat makes their infidelity a condition of the relationship. It’s a ‘take it or leave it’ form of transaction.”

Many times the root of the romantic woes—once a relationship is “opened”—is a breakdown of honesty, a key ingredient of intimacy. Certain “don’t ask, don’t tell” policies may arise that create a veil where there was once transparency between lovers. “To save their partner’s ego, they make sure to apply discretion,” says Winter, of some individuals with discreet policies. “Certainly it’s the secrets that divide couples, rather than the truth.”

However, curtailed honesty and slighted preferences for exclusivity aren’t the only factors that may compromise an open relationship. “While women are fully capable of enjoying casual sex, when it turns into a relationship—that’s where things change,” Winter says. “I’ve never met a woman who really liked a guy and said, “Oh boy, I can’t wait until he starts sleeping with other women!”

When it comes down to it, the bestselling author says, many couples dive into an open relationship only to discover that their “animal” nature manifests in more ways than under the sheets. “The rub here is jealousy,” she says, elaborating on the territorial nature of people to guard intimate spaces. “When our animal nature collides with a philosophical concept—we’re going to have a problem.” However, there are exceptions to the trend of open relationships not faring well in the long run.

Indeed, when it comes to answering whether opening a relationship will strengthen or compromise it, “it depends” rings true. Open relationships where both individuals are openly non-monogamous, for instance, can thrive. “A mutually agreed upon ‘open relationship’ is one step closer to honesty. Honesty creates intimacy,” Winter says. “The couple needs to decide how much they share with each as to the details of their relationships.”

Although many open relationships wither over time, when trust is breached, the same can be said of many monogamous relationships. The culprit of a debacle isn’t necessarily the arrangement of the romantic relationship itself, but the players’ misestimation of their capacities.

“The issue with open relationships is that few couples do it well,” says Winter, alluding to sloppy handlings of some partners and the unique can of worms that is liable to burst open in a non-monogamous relationship, including a person’s untapped insecurities and fears—i.e., one of their partner’s dalliances becoming a new romance.

In the end, a formidable open relationship—one in which a pair builds a life together—does seem to require a particular disposition toward love and sex that most young adults, and their generational elders, do not express to share. However, if both people are on a similar level of evolution, one in which they’re capable of open and honest communication (about awkward subjects), and one in which their egos aren’t diminished by their partner’s sexual escapades—or jealousy continuously inflamed by them—then, Winter says, the understanding that kept them together may keep them together.