Please advice!!!!

So I been posting asking different questions and stuff but I really need advice. So my boyfriend and I were in the shower and I started to give him a blowjob and he pulled me up to kiss me and the next thing I know he is soft again. Usually we have sex in the dark because I hate my body. But he said its not me that he has no idea why it happens so much. I'm close to giving up on sex because his problems. Ugh I don't know advice to everyone what could cause him to go soft again.