I think it’s little to do with ‘attractiveness’ but there’s a lot more at play.
I know a serial cheat who is not attractive, not wealthy, not particularly funny but women still trip over themselves to have affairs with him. Maybe he plays the victim a bit, his wife is domineering and I think women like to think they can ‘save’ him. That works both ways with the KISA syndrome where affairs start with vulnerable woman, man looking to rescue when wife is pretty in control of herself.
In my case it was the fact my husband was a good father and a good husband which ironically drew the affair partner. In the initial stages it was her pursuit. His fault for going along with it but she was the driver. I’ve known plenty like this. That’s why the idea cheats are always sleazy men makes me laugh, even most affair partners are looking for safety and commitment, the kind thoughtful family man, their choice of who will provide this is the ironic bit.
I’ve known some affairs where the affair partner couldn’t fail to notice the lifestyle they might achieve if the affair goes the distance as @Thewookiemustgo said.
There’s some that there’s just chemistry or sexual convenience.,
Why we select our potential partners is far more complex than attractiveness and women are just as good at the pursuit as men once they’ve made a choice. Which is why I do laugh at the idea mooted on here that it’s always vulnerable women and predatory men. As I write this I’m reminded of a time where I was at a concert and a woman was literally giving my husband the come on as I stood there. We’ve surely all experienced that.
Just my thoughts on it all.