Friends-with-benefits relationships (FWBs) are quite popular among U.S. college students—about 60% report at least one FWB at some point in their life. This popularity is not surprising, perhaps.

On the spectrum of completely casual (think one-night stand with a total stranger) to completely romantic (think with a spouse of several years), FWBs occupy a curious middle position. They are not quite casual—the partner is fairly well known (sometimes for years), you have a shared history of non-sexual interactions, and there is some level of emotional closeness and intimacy. As such, FWBs alleviate many of the risks inherent in more casual hookups, such as ending up with a bad/inattentive/inadequate lover, a crazy person, or a reputation. But FWBs are not quite romantic either—they lack the explicit commitment to being a couple and building a future together, and also the expectation of sexual inherent in most serious relationships. As such, they alleviate the burdens of too much commitment too quickly to the wrong person.

Aside from the obvious benefits of, well, the benefits (sexual pleasure, release, exploration) and the (companionship, support), FWBs serve two other main functions: They can act as a “placeholder” (a temporary relationship until something better comes along) or as a “trial run” (checking to see if you’re compatible with the person before getting serious).

The answer to the trial run question is usually a ‘no’: Only about 10-20% of FWBs turn into long-term . The vast majority last for a while (sometimes for years), then the sex fizzles out. And then what? Does the friendship end together with the sex, or does it somehow manage to survive the end of the "benefits"?

There’s a widespread belief that sex is detrimental to a friendship, that it will complicate matters and ultimately destroy the friendship. People have this in mind when considering FWBs. In one study, losing the friendship was the second most frequently mentioned disadvantage of FWBs (cited by 28% of students), second only to the risk of developing unreciprocated feelings (cited by 65%).

Now, a recent study published in the November 2013 issue of the Archives of Sexual Behavior should put some of these fears to rest. The research team, headed by Dr. Jesse Owen of the University of Louisville in Kentucky, surveyed almost 1,000 college students about their FWB experiences. Among the 300 who had an FWB in the last year that had already ended, a full 80% said they were still friends. What's more, 50% reported feeling as close or closer to their ex-FWB partner than before the benefits started, and about 30% were not as close. And, as you can see from the graph below, men and women had pretty similar perceptions about what happened with the friendship post-benefits.

FWBs can end in many different ways. The sexual tension dissipated (which inevitably happens over time). Or the sex didn’t really work very well. Or one of you fell in love and they/you/both decided this was a bad idea. Or one of you started a serious, monogamous relationship with someone else. However they end, it seems that once the erotic aspect has been exhausted, many don’t find it particularly hard to return to being just friends. The shared history, the emotional intimacy, the mutual liking are all still there.

But what about the 18.5% who did not remain friends? Well, not all FWBs are created equal.

Those who lost the friendship after the sex ended said their FWB relationship was more sex-based than friendship-based compared to those who remained friends. They also felt more by their ex-FWB, had fewer mutual friends with them, and reported lower overall quality of their relationship.

So if you currently have a friend (or two) with benefits, or consider turning a friend (or two) into friends with benefits, don’t worry too much about the friendship: If your non-sexual relationship is strong to begin with, adding a sexual component to the mix is unlikely to change that. And if your friendship cannot survive some physical intimacy that ends eventually, chances are, it wasn't a friendship worth keeping anyway.

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