It's entirely possible that it happened as a fluke the first time, and then after that your boyfriend was so nervous about it that it happened again and became a self-fulfilling prophecy. And you are not helping, if you tell him the only thing you want is penetration and he knows he can't deliver, of course he is not going to want to get into situations where he is just going to fail again, of course he would rather avoid it and look at pictures of girls online. You need to take the pressure to perform off him, take intercourse off the table. You like penetration, guess what, you can be penetrated by lots of things that are not his penis. If he can satisfy you, then he may eventually get his confidence back where he can have intercourse again, and if he does not last, no big deal, he can satisfy you other ways.
If you value your relationship with him then try this with him. If not, if you must have the p in your v or you will not be satisfied and I think you and he are doomed. I just hope you tell him when you break up with him that it is not him that is the issue but your narrow definitions of what sex means.