I remember some feature or another (TV, magazine, can’t remember) several years ago about greeting cards designed for one adulterer to send another. They were really precious; the usual banal poetry, but with an undercurrent of “I’ll be thinking of you while I’m with her this Christmas” and what-not. I think I had the same reaction to it that I did to the credit card company pitching specifically to illegal immigrants: it’s sad, but that market’s there, so go.
I’ve never been anything but a fierce monogamist, but even so, once upon a time it was easier for me to engage that cynicism when thinking about it. I’ve tacked steadily away from it the longer I’ve been married, and it received a violent and sustained thrust as I watched a close friend systematically destroy his family this year.
Married folks, please: be “rebels,” and actually do what you said you’d do. (Believe it or not, that really is enough reason, all by itself, to remain faithful to him/her.)