The next important, and I think the most misunderstood technique, is DB detaching. The link in the homework is pretty wordy, and if I can remember, I'll send a copy of DB detaching that is a shorter form, to get you started. I think it is hard for the newcomer b/c they are usually the ones who want to save the MR, and their emotions have been traumatized. IMHO, it seems most LBS's have difficulty maintaining even keel. Most LBS's will dramatically shift too far up or down, east or west, left or right. It's like driving a vehicle on the street. You have to stay between the lines, or take a big chance of making things much, much worse.
Your H has made it pretty clear that he is not interested in you or the MR. The more you try to persuade him to see things differently, or the more you try to vocally convince him the M can change for the better..........the more he is going to resist, He is in an emotional battle with life. He will drag down and/or fight anyone who tries to tell him what he doesn't want to hear. He cannot learn through hearing words. He has to learn visually and experiential. Anything else is useless. This is one reason facing the consequences from dishonoring boundaries works well. Boundaries are not an opportunity to lecture. He is tone deaf. He can't read anything you might suggest, nor watch a video or listen to a tape about marriage. Those features have died.
Therefore, you have to discipline yourself when you have the desire to explode on him, or try once more to just have a relationship discussion. It only sets you back to square one.
I said all that ^^^^^ to introduce the action I believe works best. Based on the mindset he has, he sees you as another source of emotional pressure. Maybe he sees it as the main source of unhappiness, or whatever. He sees himself happier if only he were free. His life is passing by too quickly and he will resist anything that gets in his way of grabbing for the gusto that awaits him. Ugh! Unfortunately, that includes having other women. If he had high morals, they seem to be gone, and currently, he is suggesting an open M. That tells me he is willing to put not only his M, but his W at risk......by inviting others to be intimate.
He is so wrapped up in himself that he doesn't see anything else. He may have an unmet emotional need, but he is currently unwilling to "do the right thing" like a logical, sane adult.
To cut to the chase, I am suggesting you become the dump-er, instead of the dump-ee. Let your attitude, GAL, personal attention, one-on-one time, home environment, family activity, etc., paint a picture for him. He sees he is losing his W of seven yrs. He no longer gets text messages from her throughout the day/night, checking in with him. If he wants to spend the night out, he has to get a babysitter, b/c his W is out getting her own life. He doesn't know what she's doing, b/c she doesn't care to share anything. In fact, there are several things about his W that tells him she is moving on. She doesn't ask him anything about his life, their MR, his future plans........nothing. She doesn't complain, preach, get revenge, nor act like a victim. He doesn't know what is going on in her head, but she looks and acts differently. He wonders if she wants a divorce. He wonders if he has lost her. I can almost read your mind. "Isn't this exactly what he wants?" I can explain more, later.
Just let me assure you that I am not telling you to do any action that goes against your personal belief system. I'm not telling you to do anything with revenge or hatred. You need to let him go. I mean, you behave as if you have emotionally let go of him. That's what he needs to feel. No pressure from you. Another thing you have to do is let go of the anger. Okay, so that will be tough, but don't show anger to him. You can be spunky, but not angry. Got to close this long post. Hope I have not thrown too much into one post. If you have questions, please ask.