This might sound pretty strange coming from a guy who enjoys messing around with married women; specifically women who "cheat" on their husbands, but....
When I get into a relationship or start having an "affair" with a married woman I insist on fidelity. If she's going to fuck around with others (besides her husband and me) then I'm not interested. As soon as I get an inclination that she's messing around with other guys, it's time to walk away. I'm sure other guys feel differently, but not me. Perhaps it's my dominant nature, but I'm not into messing around with the so-called "hot wives."
Depending on the couple and what they're into (as kinky as it can be, this is supposed to be fun) I also enjoy controlling their sex lives, limiting the kind of sex they can have with each other, like no fucking, or having them ask permission each time before having sex. I've also been a keyholder for their cuckold husbands. It's all pretty cool. I've yet to find a couple that I can both keep in chastity but it's on my bucket list!
I had a gorgeous blonde named Debbie who was married to a guy twenty years her senior. He was a true cuck, a few years older than me and surrendered his manhood to the both of us. I held his key for a few months and Debbie loved every minute of it. I found out she had seen another guy while I was gone for a week. I called her, told her it was over and mailed her back the key.
Yes I'm controlling but many couples like it that way. So, if a woman wants to fuck other guys besides me, more power to her. I'm just not going to be one of them.