Guys, What would compel you to cheat on your wife... with her sister?

I was working on a project with a friend who's been married 30+ years to a guy I can only politely describe as... not nice looking. She, by contrast, is a very peppy, nice-looking gal a little older than me. Great shape, personality, work ethic, community spirit, etc... the whole package. Out of the blue one of her kids calls to check on her, apologizing for something their father has done. Since the room we're in is the only private space in the area, I offer to get up and give her privacy, but she shakes her head and wraps the conversation up. She then reveals that... after 30+ years of marriage, three kids (the youngest 25, the eldest 30) and all the sacrifices I've watched her put into her family and spousal life... he was caught cheating on her... with her sister.

Now... many guys cheat, and while I don't get it -- especially if they are married to someone like this -- I can't understand why it should ever be with their wife's family member. What's up with that?

Are we just that "interchangeable" to you guys?

It's so disheartening to those of us who were raised to save ourselves for the "right guy". Smh.

Guys, What would compel you to cheat on your wife... with her sister?
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