Well, why am I breaking up with this person? Is it because they're terrible in bed, or because they're a twitchy weirdo, or because they stole my life savings? Or is it just because we're not really all that compatible outside of the bedroom? Because I don't see a life with them? Because they're gay and I'm not or vice-versa? ..
..
Obviously, the answer's going to change based on the scenario, but in general, probably not. I'm not that cold-hearted...

I have. Many times...
Are you asking because a guy slept with you and that makes you think that he still has sweet love for you and therefore wouldn't be on the verge of breaking up with you? Or because you slept with someone last Thursday, and then he dumped you this week. And how could he have done it?..
And then there's the awful, we just decided we're breaking up sex. Sigh. But that happens too...