I have had a friend with benefits and it came in two stages. The first stage, I was very much in love with him and he had had a crush on me but got over it, but still found me attractive, cared about me deeply... and wanted sex. It was confusing and I slept with him largely on the basis that I was sure that he would come to redevelop his feelings for me while insisting to him that I was a big girl and could make my own decisions. In the end we came to our senses and realised it was too messy a situation to continue.
The second stage came three years and two boyfriends later, when we went 'Hey, remember when we used to have casual sex? That was cool, let's do that again.' At this point, all romantic feelings for each other had gone and our friendship wasn't particularly close either. It made it so much more simple. However, this was the point where I realised I can't really do the sex-without-romance thing. While I'd come away from a night with him feeling satisfied and empowered, I had a tendency to suddenly break down in tears for no apparent reason later in the day, full of feelings of loneliness and abandonment. I still don't really know what was going on, but when this kept happening I had to tell him that it seemed like I couldn't get a grip on this kind of relationship.
However! I regret nothing, and feel like my relationship(s) with him has made me much more aware and in touch with my own sexuality and agency. We had a very open friendship as it was, so for all the time we were very honest with each other and I felt very safe and happy with him. It's just that, unfortunately, I guess I need more from a relationship than sex. If that one thing was different about me, it would have been a perfect arrangement (that second time, at least).
Captcha: two cents worth. Appropriate.