going soft?!

Help ladies have this happened to you. So we are having sex and we are so Into it the guy is sweating so much which I don't mind. He tells me to stop appereantly he has gone soft?!! Why?! I feel like maybe it was me? He says he was tired idk then if i start sucking him he gets hard again and we keep going. Yes we last a pretty long time after taking breaks? Please tell me your thoughts. He says he hates sweating and that's why which I doubt it! Idk what it can be we are so attracted to each other and we have crazy sex which we both enjoy. But this has happened a few times