As you said, giving in to his pressure ended up making you both unhappy. Worse for you--sexual contact under pressure is tantamount to assault--but not the experience he was hoping for, either.

In my mind, the best part of any sexual encounter isn't the physical pleasure, but the moment of discovering you have reached your YES together--that what's about to happen is exactly what you BOTH want to happen.

I would be infinitely happier sharing kisses that we both want than having intercourse with someone who isn't really enthusiastic but just wants to keep me happy.