i think there is something really hot about allowing your dick to do what it wants, while being fucked. i dont like to jerk off a lot, when my BF is in me. . . just do my 'bottom' job, and let my dick and my hole do their own thing.
I'm the same way. I don't jerk myself off usually while I'm getting fucked, but my cock naturally gets rock hard. I've had guys comment on how hard it gets. I love it when a guy has been fucking me for some time, then squirts some lube on my dick and starts jerking me while he's pounding my ass. I'm usually a dribbler, but I've shot cum up to my chin when he's done that.
In porn, I've noticed that the top rarely touches the cock of the bottom. I especially enjoy when the top does jack off the bottom. So hot.