As far as rough sex goes, I think of it this way. In the Filipino language (Tagalog), there's a word called "gigil" that I've never heard any kind of English translation for. It's that overwhelming almost giddy emotion to pinch someone's cheek (for example) because you think she's so fucking adorably cute.
That emotion, taken to a sexual level, is what drives me sometimes to just go harder and harder and rougher and rougher until I just let go. It's almost like a switch flicks on and I watch her ass bouncing as I fuck her pussy when we're doing doggy... such a cuuuuuute fucking ass... I must.... NGGGGNNGGNN... I must slap it!! Oh my god, this feels sooo fucking good, I gotta hang on to your hair, pull it back until it hurts and fuck the life outta you! Holy fucking shit... oohhh, a neck! Lemme suck it, suck suck suckit!!
MMMmmmm... fuck fuck fuck ... I gotta ... I gotta.... FUCK I GOTTA BITE YOUR SHOULDER HARD!!! OH MY GOD, THIS FEELS SO GOOD, I GOTTA PIN YOU DOWN AND JUST FUCK YOUN UNTIL YOU CAN'T WALK!!
yeah, like that. That's GIGIL.