Well, I think casual sex is fine for 2 people who are both looking for the same thing, but it's not for me.
I've had my share of fuck buddies in the past, and for the most part we remained buddies after the sex stopped. The problem is, I just found it cold and meaningless after a while. Now, for me, there has to be at least some emotional connection there or it just doesn't work. It doesn't have to be love, but there has to be a mutual affection that goes beyond friendship.
However, I had to have lots of casual sex in order to figure all that out
