Today I failed to maintain an erection while (attempting) to make love to a woman I am very close to. While I was very turned on in my mind, and was very aware of how sexy she was, none of these feelings reached me down there. I failed to get erect during foreplay, became slightly erect (we'll say halfmast) when she paid specific attention to my penis, but went limp halfway to climax.

My guess is that this was from a lack of cardio exercise, or a slight perversion I have. When I fantasize, it is often a fantasy of a girl teasing me, or being a little forceful, rather than straight sex. However, she did things that I KNEW should be turning me on, and after I went limp, I didn't feel anything else to revive my erection. In the past, I have occasionally felt a less than full erection when with a girl, but rarely when masturbating (it works fine then). I am too young to experience erectile dysfunction, so why do you think this happened? Any suggestions on how to shake this problem?