L2L, I have also racked my brain...here's my personal conclusion. See if you can relate...my parents weren't drinkers/druggers but they had volatile, loud arguments, screaming, yelling, throwing things, tons of drama. I was the one who comforted my mother as she lay on the living room floor, sobbing in the dark, curled in the fetal position, after my father left the house in a rage. She would tell me she was trapped, wanted to leave, him, had nowhere to go and I would sit beside her, trying to say and do things to help.
It upset me so much to see her in that state but I felt needed. Somewhere deep in my psyche registered: So men leave you when you don't conform to their wishes and I am useful when I am helping others. With the AM I've been referring to here, I became a walking, talking, man-pleasing doormat. And we know how well that worked out. He walked over me & out the door.