I dated on fucked up chick that didn't want to orgasm. I never understood it. She would sit on my face for 10 minutes and once she gets to that point she pushed me away, same with sex, I'd bang away and she'd start moaning heavier and louder and once she got close would jump up then suck my cock, swallow it and everything.
I deduced that she was probably some squirter and was too embarassed to drop a gallon of pussy juice on her bed or something.