He rarely gets off

I've been dating my current boyfriend for about 3 months. We have great sex and he gets me off more than anyone I've ever been with. Problem is that he doesn't get off every time. He gets off maybe half the time. He says he is satisfied and that he has always been like this, but it makes me feel like I'm not good enough... He tells me not to worry about it because he is more satisfied with pleasing me than himself. Anyone have this kind of issue? Do you think he should see a doctor? I'm just not used to being with a guy who can't get off every time we have sex. This isn't normal for me.