Need help😩

I need help! Me and my boyfriend have a good sex life....when we have it. He struggles to get it hard and if he does he struggles a lot to keep it hard. It makes me think I'm not good enough and we've talked about it so many times because he gets so angry and just storms off straight after we've 'tried' it doesn't help that he really wants children, we both do but it's going to be a struggle without having sex! Advice please, what can we do??

He won't go to the doctors he's too 'proud' as such!