So I'm mostly concerned that this could be a health issue. My boyfriend is 25 and before we started having sex he got tested for STDs as did I. Both came back negative and I'm on birth control so we stopped using condoms after a couple weeks of having sex.

At first I thought maybe it was because of the condoms because I know that many guys say they can't feel as much with one on so it's harder to maintain an erection. But even though we stopped using them he still rarely has an erection the full time. He is the biggest guy I've been with and didn't know if it being big has someting to do with it? He's almost 26 and has been keeping up on things like testicular cancer screenings etc... and has always been perfectly healthy. He exercises everyday and his body fat percentage is average. He does smoke cigarettes but a pack will last him about 2-3 days so he doesn't smoke that much either. He eats very healthy and stays away from junk food, sugar etc... mostly drinking water all the time.

He swears it has nothing to do with me and I believe him. He does get a full erection right off the bat but no matter what it goes away after maybe 10 minutes. I'm afraid to say something to him about it because I don't want him to feel inadequate or like he doesn't please me. Could this indicate something else wrong with him physically?