@outherealone My sub, or affair partner as you put it (I suppose quite rightly although I see an affair as something more than just physical) likes humiliation, pain, restraint and suspension, throat fucking, hard spanking, whipping, caning, face slapping, choking. The list goes on. In a nutshell, she's a true masochist - nothing has ever proved too extreme for her.
As much as I would love it if my wife one day said she wanted it rough, I don't think I could ever bring myself to choke her to within a whisker of passing out, or spanking her so hard my own hand hurts, or caning her so hard that the cane leaves white raised marks on her skin, forcing part of me down her throat and holding her head there while she fights the wretching and convulsing. I couldn't do any of that to my wife.
Sure, I could tie her up playfully and give her a light slap on the arse if she wanted me to but that's about it. No way could I slap her face or queeze her throat or in any way risk physically harming her.
I don't expect anyone to understand and I fully expect the majority to think I'm a psycho (which I am absolutely not) but that's how it is and it's why my sub and I have such an arrangement. We both get what we want out of the sexual relationship and no one else judges because they have no idea.
I could never have an emotional relationship with my sub, we're not compatible in that way. We are however compatible sexually.
Likewise, I could never have a BDSM relationship with my wife. I love her too much to be able to inflict physical pain on her. Even if it's what she said she wanted.
Ironically, by doing what I'm doing I risk inflicting emotional pain on her which is as bad but I do what I can to make sure that doesn't happen.