Arousal Issues

So my boyfriend and I have been together for about a year now, and he's always had this be a bit of an issuse but it's become such a problem. I need advice. He's 22 and I'm 21, and he has issues staying aroused during sex. So we stopped using condoms and I got on BC but it's still happening. And I guess I want to know how to fix it without having to go to the doctors. Any advice?