to me, it sounds psychological rather than impotence... if he was, in fact, impotent, he wouldn't be able to "get it up" in the first place. Ok, I'm gonna be very, brutally honest with you. Years ago, I was dating a girl who I had been pursuing for a long time, and she finally agreed to a relationship. The first few times I tried to have sex with her, I'd last only a few minutes into sex before I got soft. I actually went to see a therapist because of it, and it wasn't until then I realized how much I put this woman on a pedastal, how I couldn't believe I was having sex with a woman who was so wonderful, beautiful, cool, amazing... that was what my mind gravitated towards, and for some strange reason, I couldn't keep it up..
I ended up spilling my guts to my therapist, who pointed this out to me. He said something along the lines of, "when you have sex with a woman, what are you thinking about?" And I told him what I said in the prior paragraph, about thinking that, while I was having sex, that I just couldn't believe I was having sex with someone so amazing as her, that I wasn't focused, that my mind was completely detached from the present, crucial moment. And he told me that when I'm having sex, just stay focused on the act of FUCKING, the physical, the thrusting, the pure sex act alone. Next time I found myself in this situation, I had NO trouble staying hard, finishing the deed, and the woman was practically in tears, it was so good. So, long story short, his issue sounds far more psychological than it does physical, and that this might be all he needs - to just stay in the moment and concentrate on the sex act alone rather than any other stray thoughts that might be swimming around in his mind.
Ok, guys - now that you heard my story, feel free to bust on me, but I'm speaking the truth - I HAD that problem, but it was only once, and I learned a lot from it. It was weird at first, but it happened, and from then on, I knew what to do - STAY IN THE MOMENT!!! =)