Re: Boyfriend couldn't finish...
It is not you. Believe me! It was all nerves on his part. Most women can't understand the fear many guys have of not being able to last long during sex, or at least last long enough. He was obviously trying there towards the end after he had done his job of satisfying you, but sometimes a guy just can't get there when he is nervous.
Indeed, some men can be very sensitive at first and have to fight really hard to not come too soon (which is really difficult and often impossible), and if they get past that stage, they kind of lose all feelings and can't come at all no matter how hard they try. Strange, but true -- the harder they try, the more they fail until they have to give up in frustration.
It may be that he tried so hard to please you that he simply "lost it" and couldn't get it back. Don't make any big deal out of this. He already feels bad, and the male sexual ego can be pertty delicate. You don't want to make him feel that you wonder that it was YOUR fault when it wasn't.
And, regarding oral, some guys have trouble coming this way for whatever reason, even though they enjoy it. I don't know if he was trying not to come during oral, but next time you might encourage him to come that way so he has a clear signal that it is alright.