So if these whys are blaming my BH and essentially not good enough whys and I need to dig deeper. What exactly is an acceptable why that's not blaming? Does it have to lead back to FOO issues or some other deeper trauma or possibly a resentment?
I really would like to understand this. And if this is why we are stuck where we are then I need to change, learn or like you said, dig deeper for something else.
The "something else" is character. I expect that's hard to hear because we all like to think we're people of good character. But when our stated values fail to align with our actual deeds, there's a gap in our character which allows us to say "yes" to perfidy. In marriage, we claim certain values as our own, things like Fidelity, Honesty, Respect. But in practice, sometimes people aren't a strong in their beliefs as they think they are. There's a "but..." in their core values. ie. "I believe in fidelity, but... not if I feel disconnected". The value of fidelity is weak and permeable, subject to change, and not immutable as it should have been. People who truly honor their core values protect them by building strong boundaries around their behavior.
Character >>> Values/Beliefs >>> Boundaries
Once you know what you truly believe in, you value it. You honor it. It's a part of who you are, so you protect it with boundaries. I believe in fidelity. My value of it is strong. It's never subject to threat because I never allow potential interlopers to get that close to me. Boundary. I don't even think about it. It's ingrained, attached to my core value.
It's a difficult thing to have to reevaluate yourself and maybe realize that you aren't the person you thought you were. But, when you start with your core values, the things you truly believe in, you can build from there. WHY was your value of fidelity weak and permeable? Why was there a "but..." in your stated belief, your vow? Once you roll up your sleeves and start thinking about it, you can start figuring out who you really are rather than who you thought you were. It's not like you can't change, but you can't fool yourself either. You have to REALLY honor the things you purport to believe in. Otherwise, the belief isn't strong enough to hold your boundaries.
As far as your original question, what it takes for your BH to stop internalizing YOUR behavior... he has to ACCEPT that he has no control over your character and your choices. Nothing he did, or didn't do, could cause you to cheat if your core values were solid. If your core values were solid, those boundaries would have been there. BS's feel sometimes like they need to be paying attention to the "but...", like if he were making sure you weren't "disconnected", it wouldn't have happened. That's just a subconscious control mechanism. There's NOTHING he can do which will cause YOU to honor your beliefs and maintain boundaries. Only you can do that.
It's sometimes VERY difficult for a BS to stop internalizing the injury. It's attached to the ego, you see. We wonder how our WS could have forgotten us, even hated us. It's difficult to accept that someone we loved and married is capable of the mental gymnastics and compartmentalization it takes to bypass their own values and not SEE us. Also, not helpful is that the first excuses we typically hear from the WS are blame-shifting ones that are seared into our memory. We hear it said that the first person a WS lies to is themselves, and I think that's true. It's how the sausage is made in terms of mental gymnastics and compartmentalization. What's missed is that the REASON for those lies is to paper over the injury they do to their core values system. The WS doesn't want to believe that there's a flaw in character, that their values are chock full of "buts...", weak and permeable. Instead, they focus on those "buts..." as their truth. The BS will sometimes drive themselves mad, trying to make sure all those "buts..." are addressed, remediated. All along though, it wasn't the "but..." which was at fault. It's the fact that there was one at all. Eliminate the "buts...". Work the core values. Take true responsibility for your infidelity. Call your WH out when he internalizes. Remind him that this is about YOU and that you've got a plan to remediate your flaws.