Sex researcher Justin Lehmiller recently answered this question on his site, Sex and Psychology, looking to the research to give the reader who posed the question some good news: The friendship isn't necessarily doomed, he writes.
One study, for example, found that about half of the 308 participants said they were either less close with their former FWB pal, or that they were no longer friends at all. But this also, of course, means that about half did manage to stay friends — and about one in seven people told the researchers that their friendships were even better than they'd been before they started hooking up.
The obvious caveats: This, as is true with many studies in social psychology, is a study of college students, so the results very well may not be universally applicable. But for those college students, at least, it suggests that while sex may make things weird for a time, it doesn't have to ruin the relationship. It's complicated, as they say.
