I'm so sorry you're dealing with this. We always say this and we feel it, but I really really am sorry for what you're going through as I don't see a way out of this. If I were you, if this were happening to me, and I had a clear mind, I'd just pack it up and get a divorce. Or end it (not clear if you're legally married.)
This is a serious, serious, serious problem, and it's a problem that's emerged with a lot of guys because of the nature of porn now. The process of getting porn is different because...it's right there on the computer or phone, it's so easy to get, there's so much of it and I think just the nature of consuming it is different than perhaps it was before when there were magazines or videos or maybe a TV channel or two. It might have even been communal at some points in the past or something you shared with a partner but the physical nature of availability I think interacts with the brain in a different way now. Like social media does in general. Maybe someone else here who is more familiar with this specific topic can weigh in, but I think this has become a SERIOUS ADDICTION for a lot of guys. And a hard one to kick as sex is innate, and not like a drug that...we're not born taking drugs, it's external to us, there's no natural drive for it. Gambling is external, drinking is external. But sex is innate, it's a part of our biology. The drive is there for most of us.
I tend to think porn now, involves and creates CONDITIONING to certain types of sex. And the sex has gotten more and more extreme and often violent. Choking has become a real problem, even among young men who because of the porn they just casually see, they think this is a normal part of sex. And...of course it isn't. Some people can frighten, injure or even kill a partner with choking, in particular....but you would be surprised at how many young people think this is something to do. I have even come across this in fan fiction about animes (I'm an anime fan - some people write romances about their faves). I was surprised to see this practice coming up as a thing.
I think the Dom stuff is like this...maybe your man has some kind of natural submissive tendency, but whatever he has been watching has conditioned him to think of this AS SEX. This IS what sex has become to him. This is why he can't get off with you - or probably with another "normal" woman. This is why he masturbates - when he does that, he can think of these practices. That's why he's obsessed with this person, it's not her, it's the practice. He's become conditioned to think of this AS SEX. Once someone becomes conditioned to something AS SEX, like maybe a foot fetish? it's very hard to get rid of that. It's very hard to deprogram.
I don't doubt that he loves you but this is going to ruin your life and right now he's not available to you in very real, basic ways. And this include finances too because this WILL cost money. This woman and other Doms are probably not doing this as a charity. He needs to find someone who specializes in de-programming this kind of porn induced sexual conditioning and get back to a point where he doesn't NEED this to function or imagine (for masturbation). I don't know how many of these kind of counselors are out there. Maybe one of our other folks here has some ideas about de-conditioning because if he keeps pursuing this, he's going to ruin his own life, IMO, but you can't help that.
If I were you, I would end this. Not only on the grounds of infidelity because he actually has tried to be somewhat honest and open with you, but this is not normal sexuality and it's going to get worse and make you miserable. You can't have a relationship where the sex is all based on something or someone else and not you or your needs. This has become a compulsion. I'm sorry, you can still care for him, but I don't think this is livable, and I'm not sure how it can be salvaged.
I hope we can find others with some good ideas here, but I would get out of this and stop interacting - just by interacting we keep them in the fantasy - they have to have a reason strong enough to kick any addiction or compulsion. Don't go along with this.
[This message edited by BondJaneBond at 8:29 PM, Thursday, February 26th]