Somewhat TMI... sorry!!

I’ve had a lot of sex, and I’ve had a lot of really great sex, but no matter how good it is I still can’t seem to cum. I can’t even get myself to do it with a vibrator. It’s like I’m pleasured but never past a certain point. I recently started dating this guy, and he really wants me to, and I can tell he’s trying really hard to help, so he seems slightly bothered by the fact that I don’t. I was wondering if there were any tricks to getting yourself to?