I am going to tread lightly here, because as BSes we have been violated already. The scale has already been tipped hard to one side, and it isn't in our favor. All of this is totally unfair.
I can relate a lot with what you are saying, because my H spent years and years trying to figure out why my desire for him felt low. After the standard couple of early years, things got kind of sparse -- sex itself was good, but there wasn't nearly enough of it for him. I thought there was something wrong with me - that was the message. It was a terrible, depressing feeling; I can't emphasize that enough. Of course there are all these messages too from society and girlfriends too, that waning sex is normal and to be expected in a marriage. I would try to do things to fix it, talked to my doctor, read books, etc., but nothing seemed to help.
My husband had an alternate reality going on, and he imagined that I must feel desire like he did, but that I must be directing it somewhere else. This is part of the rationalization he used for the affair. (I can't imagine how difficult it would have been if I had directed it elsewhere, which is what you guys are dealing with.)
My H thought that it must be that I found him undesireable, and this ate away at his self-esteem, and his sense of himself as a man. Coupled with other mid-life stuff, and his FOO, and a woman who was willing to step in and tell him what a stud he was. . . well, it set the stage for the affair.
But, the truth is, I was just switched off, like a light. A little of that was my fault, but it turns out, quite a bit of it was his. I didn't feel special, desireable, or wanted -- I felt like my husband just wanted to have sex, and it didn't matter if it was with me or not. Of course, him having an affair didn't help that line of thinking! What he/we didn't realize, is that he had a lot more power than he knew.
So, what has really helped us is my husband making me a priority, and him getting curious about what makes me feel special and wanted. He had no clue that this was his job before, and I guess I didn't really, either. It just goes to show how differently wired men and women can be. We are now both much better at this. I want to emphasize that this takes a lot of communication, because doing just what you think makes your spouse feel that way may not work.
I can only imagine how hard it would be for a WW, who probably on some level feels incredibly shamed about herself and her sexuality, to allow herself to open up enough to accept this, but in my opinion it is key. If you will work at becoming a specialist in what makes her feel special and wanted, my bet is that the desire and passion will return. It is like magic.
I know it sounds like I am putting the burden on you, and as BSes this is totally not fair. But, I do think it pays good dividends for everyone in the end. (And, obviously, she should be doing the same for you as well.) His Needs, Her Needs is a good place to start, if you haven't read it.
Looking to feel special and desirable in an affair turns out to be poisonous, and our waywards learn that. That is why the whole back of truck, concession stand stuff is a bit of a parody of real, honest, loving, intimate sex. But, for Mr. Bionic and I at least, we have learned how to be better at providing those feelings for each other, even after being married 20+ years.
Good luck.
[This message edited by bionicgal at 10:49 AM, March 30th (Monday)]