Is it me?

This guy I recently started seeing took me out lastnight and I went back to his place. We had both had a lot to drink because it was Christmas and he told me that he can't produced enough sperm to make a baby (I know I shouldn't worry about this now but long term thinking it kind of worried me) anyways, we went to have sex and he was able to get it up after I gave him a bj but when we started to have sex he got soft. We tried again another time and the same thing happened. He felt bad and said that he would make it up to me in the morning but I ended up leaving before he woke up because I had to work. I should also mention he smokes a lot of weed. Just wondering if there is anything I can do or if this could just be a one time thing because he was drunk?