So, here's a twist: I (the girl) orgasm super easily, while my boyfriend does not--in fact, he's only come during sex with me once, and that was the first time in his life (he's almost 30). He can come if I go down on him (although I am the first girl he has been able to with and he didn't for the first few months of our relationship) and it took him a while to even come when I used my hand. He thinks something is physically wrong with him, and that something wasn't done right when he was circumcised. He may be right--his most sensitive spot is actually a little bit of what seems like leftover foreskin on one side of the head of his penis. I know he CAN ejaculate (and does pretty regularly with non-penetration methods), so it doesn't seem to be a problem with his plumbing. Have you ever heard of loss of sensation like he describes?
I'm sure the problem is compounded by other stuff. He's less self-conscious about this than he used to be, but if in 10 years of having sex YOU weren't able to orgasm, it would just be like the biggest, most embarrassing elephant in the room, right? I can't help but think that there's something more I could do. I really, really want him to be able to come again, and now it's all I think about! Before he did, I didn't think much of it because he had said he wouldn't be able to and I just went with that. But then he did, and it was amazing for both of us, and now it's like my hopes are up.
Wishing for Coming
I don't think that your boyfriend's issues are physical ones - a circumcision (good or bad) shouldn't affect his ability to orgasm (though yes, it can affect his surface sensitivity) - for most men, it's primarily a pressure/friction issue, not a skin-touch issue, like for women. And the fact that he can come "pretty regularly" in ANY way, means that his "plumbing" is fine. So that's the good news, since most physical problems don't have easy answers.
But what I think is happening is that he has some mental difficulty with intimacy and sex - if he can regularly come through masturbation, but has a harder time with a partner, then something larger is going on. Kudos to you for being so caring and concerned about his pleasure, and clearly he feels more comfortable with you than with previous partners. But there may not be anything else that you can do - this isn't a matter of your technique or enthusiasm. And pressure on him to come, from either of you, and no matter how well-intentioned, may actually be making it harder for him. Has he ever thought about talking with someone? I don't think he's crazy, or "sick," but a few sessions with a therapist may help him to unlock some of these things.
Best of luck,