So I had known this guy for a couple weeks and one night I ended up being really drunk and we had sex... he was not drunk. We were doing our thing and he ended up getting limp. He seems very into me so I was really shocked and didn't know if he was just nervous or what, he isn't that type though. He told me it had never happened to him before, so I was wondering if you all had any idea's.

You don't have to be drunk for alcohol to have that effect, but don't take it personal, as he may have erectile dysfunction, and a doctor can cure it. Maybe he just lost his concentration, and freaked out. How old is he, and is he on meds, or any type of drugs?

Stress, performance anxiety, poor sleep, depression, illness, drugs, meds, medical conditions, too much self stimulation...

A lot can go into this. No singular answer. Sorry.