Why do I lose my erection when I put on a condom?

I care for my girlfriend, whom I have been seeing for a few months now. I have no problem maintaining an erection when she performs oral sex on me. In fact I can climax twice in a relatively short time. We have, however, been unable to actually engage in intercourse, since when we go to put on the condom, I lose my erection. I'm not really having too much of a problem getting erect (i.e., I get an erection, and may lose it early on, but I am able to get and maintain another one for oral sex). What could be the problem? Stress? A lack of physical attraction? I will be grateful for any answer you can provide me.


Is there a connection between Depo-Provera and hair loss?

I have taken three Depo-Provera shots. My hair started falling out excessively several months ago. In looking for answers I found out that this is a side effect to the shots. I was not informed of that before I took the shots. I saw in one of your Go Ask Alice! answers that depo-provera suppresses the Follicle Stimulating Hormone and the Luteinizing Hormone. What is this hormone? Is this what makes my hair fall out? And do you know if there is anything I can do to stop it? My next shot is due by May 15 but I am not going to get it. Thanks.