I noticed it once before but wasn't sure of it until it happened again last night. My bf and I were in the middle of have sex and I was enjoying it until suddenly I noticed that he lost his erection. I didn't know what to do and went along with what he wanted to do. He kept trying and I can sense his frustration. Finally I had to stop and made up an excuse so we could stop. I'm curious but what would cause something like that to happen and how should I talk to him or if I should even talk to him about this?