We never cum?!?

I never orgasm from vaginal penetration, oral sex or fingering. It feels nice but I can never "let go." He never cums either, not during sex and he doesn't come from handjobs or when I give him oral. We've had sex for about four hours before and neither one of us could cum. We can both masturbate and cum, but even the last time he masturbated in front of me he didn't cum but I did. I don't get it?!?! It's SO frustrating!!