His didnt get hard! Is it my fault?

so the other night, this guy who i am extremely ually attracted came over my house and we ended up fooling around. I lead him up to my bedroom and after lots of kissing, caressing and , we begin to derobe and hes not hard!! I begin to jerkk him off a little bit and it would begin to get hard, then go completely flacid. I was so pissed and now im wondering, could it have been me. I have been told im gorgeous and this guy also thinks so! He got really upset about the situation and seemed like he really cared. How do i know when something like this is my fault?