Maybe around year 8 or 9, I decided that we always had the same arguments (cleaning the house, grocery shopping, saving money, etc...typical stuff). So one day I just said to myself, "I'm not going to argue anymore and I'm not going to say anything about the stuff that bothers me." If the house was a wreck, I'd clean it myself or let it be dirty. I did all the shopping, all the bills, all the appointments and schedules...I just did it all and never again asked for help with anything. I also stopped complaining about my wife never being there as well.
By doing these things, the arguments almost completely stopped because there was nothing left to argue about. We lived basically like we were single, did some things as a family, and we just sort of existed for the next 15 years. And honestly, this was more terrible than getting screamed at and slapped. At least back then there were good times and bad times. I just felt alone though and it was depressing to be married but living like I'm single (not in the dating sense...just in the general lifestyle since I did so much alone).
If I hadn't made that change in year 8, there's no possible way we made it 23 years. And I still don't completely know why I gave up my values and morals to let her just run free. I'm not autistic, but at the same time there has to be something different about me since I just lost the will to keep fighting back. I just hated everything about arguing and I still shy away from conflict today.
I noticed a similar situation with my parents. I didn't understand all that was going on as I was a child but when I was about 9 years old, they had big arguments. Dad was already doing a lot of parenting.
By my teens, these episodes seemed to be lesser, but my father also seemed to be resigned to just doing whatever BPD mother wanted him to do. He also seemed less engaged- in general.
I don't think he had any idea BPD mother was mentally ill in their early years of being together. I think he must have known later but he didn't mention BPD.
Not knowing why one would give up their values, as Pook said- I don't know either but I think maybe the constant stress, walking on eggshells, to give in also results in momentary- even if temporary, relief and that may be all one can manage in the moment.