I was with my ex wife for 10 years and didn't once cheat on her, but I can't say that if our relationship survived, I would have been for much longer.
I can only remember 2 HB10s making a serious play for me during that time.
The first was a drop-dead gorgeous Norwegian woman, "K." I think she got off on the "forbidden fruit" thing, I was the king of AFCs at the time, an outspoken proponent of marriage, and raised to believe that men in my family didn't screw around on their wives. I just had my second kid. I was very in love. I let it go regretting I hadn't met K sooner, but not staying true to my vows.
A year and a half after that I met C. My marriage was falling apart because my wife became a heavy drug user. I was beginning to shed my AFC exterior and resent my station in life. I regret missing out on C. She was a beautiful twenty four year old doctoral student. Brilliant, with a body that belonged in nudie magazines, and an exceptional person besides that. Truly an "A-List" woman. C helped me through some rough times, was a great friend and wanted more. But for a number of reasons, I let it slip. My head was not screwed on straight, and my kids needed me around all the time (their mom was in rehab). I regret not cheating with C.
I've never cheated, but to be honest, if I'd stayed married for 20+, I'd have strayed. Sex gets less frequent, that's reason enough. Who can deal with getting laid twice a month? That's how often most of my married friends are down to, many of them less than that. Dealing with that is bound to wear on you after months or years. Why should you sit around getting prostate cancer because some 55 year old hag, who should be grateful for any attention you give her at that age, doesn't kick it down enough?