When I'm alone, I have absolutely no problem reaching orgasm. I can use my hand, a vibrator, or even the massage on the shower head and I always get off (clitoral orgasms, I mean. I've never had a vaginal one) and usually in under five minutes.
When someone else is involved though, I have a very hard time coming. I have every other reaction that goes along with an orgasm: flushed skin, shaking legs, even my face will tingle or go numb, but I can't cross that threshold.
I have my boyfriend do the exact same things that I do myself. I've even gotten a vibrator involved and it still won't happen.
Help! He's started to get frustrated and think that it's his fault. I keep telling him that it's not. I don't know why I can't finish, but it's not for his lack of effort...