My boyfriend can't have sex

Embarrassing but, my boyfriend can't have sex. He can't get hard. We've tried therapy, an open relationship, and pills. Nothing works. I worry he's not attracted to me though he claims he is. He has always been attracted to bigger women, which I am not. He also was a virgin when I met him, I'm the only person he has had sex with. We weren't in an open relationship anymore when he cheated on me with guys, all glory hole type situations. It makes me feel so bad about myself plus, I have a high sex drive but the open relationship made him uncomfortable, so I'm not allowed to see other people anymore. Does anyone have any thoughts or advice? A lot of the people I have talked to about it think that I'm selfish for wanting more sex and for wanting to open the relationship again.