I swear if the affair doesn't kill me this list might.
1. The fact I wasn't handsome and that she was never into me sexually. She let me in on this one this morning. See here for details: http://www.survivinginfidelity.com/forums.asp?tid=567119. Cliff notes is that she married me in spite of not being attracted to me. She apparently found the AP much more handsome than me.
2. The AP had an erection when they started to fool around. This one is pretty fucking choice. Here is the story on this one. For the first few years of our marriage I was Johnny on the spot. Then she increasingly and increasingly rejected my sexual advances. She had a sexual dysfunction that made her almost unable to have an orgasm. She had very little interest in sex. After years of this, I admit it, when we would start to fool around, I didn't have an erection right away. My mind was thinking about how I could no longer give her oral sex, kiss her breasts, touch her body, or give her an orgasm. I was thinking about the fact that she really wasn't that into it. I think it is pretty fucking reasonable that I didn't have an erection at this point. It is worth noting that I did eventually get and maintain an erection 95% of the time we had sex. Most tellingly, since Dday her sexual dysfunction has almost entirely resolved and she is again turned on by me. I am again like a steel pipe as soon as we start to fool around. So it is clear that it was her sexual dysfunction, not any problem with me, that caused me not to have an erection right away. So to hear something like, "well, AP had an erection when we started to fool around and you didn't" is just fucking brutal. (More info, not sure if it is relevant: She has said that she can count on one hand the number of orgasms she had with the sexual partners she had prior to our marriage. She did not have an orgasm with the AP (confirmed via poly). Now I give her oral sex and she weeps and practically passes out from the orgasm. So, again, how am I failing sexually?)
3. The AP had bigger muscles in his chest and arms. Well, I guess I can't argue with this one. I haven't seen a picture of him with his shirt off, but I'll take her word for it. If this is that important to her then there is not much I can about this one.
4. I demanded that we go to MC. This one did, in fact, happen. I knew we had problems in our sex life. I knew that the root of the problem was the sexual dysfunction I described above. I figured that was the best chance to fix our sex life. She now says that she felt overwhelmed by therapy (in spite of the fact that 9 months in we still hadn't talked about sex).
5. She was bored. I guess this is true. Not sure it is a great reason to have an affair.
6. I didn't give her enough responsibilities in running the household. She said that she liked having control of something (the A) for the first time.
7. She was turned on by the fact that AP spoke a different language and she liked to share this with him. To make this one work I think you have to ignore the fact that one of the things that initially made us interested in each other is the fact that we each spoke the same foreign language (a different one than AP spoke).
8. She took me for granted. She said she thought I would never find out, and even if she did allow herself to consider this, she figured I would be hurt but that I would forgive her. She figured it was only sex, and not even that much of it, and that she wasn't in love, and that it wasn't taking anything away from our marriage. To be fair, she says this is wrong, but that that is the way she felt.
9. She was selfish and felt entitled to the affair after all the hard work she had done in the marriage. I'm not going to disagree with this one. I'll just let it sit right there. Again, to be fair, she says this is wrong, but that that is the way she felt.
In summary, she was with someone she wasn't attracted to, who she found to be a bit of a pain in the ass, and who only spoke one foreign language. Then a real man, with muscles and an erection came along. And that is why she had an affair.