For me, it's pretty much like cyn said. I once tried to have "spite" sex, but couldn't get into it and it made me more miserable. I need to get past the broken relationship first.
This may be somewhat judgmental, but it seems that it's sort of a macho thing to help SOME guys move on by reinforcing the idea I've heard from certain men that one
hole is as good as another. I realize that statement is disgustingly sexist and it's definitely not mine, nor is it that of all men, but I've had some frank conversations with quite a few men (in their 30s and up) who've basically said they'd fuck just about anyone, given the opportunity.