As one of the people who stayed for 20+ years of it, I feel like I must share this with you.
My 20yo daughter asked me for relationship advice today. She had a big long explanation of *why* her boyfriend is like he is. (BTW, this is not an addiction issue) After going into much detail about the causes behind her bf's behavior, she asked me what I thought. I told her it doesn't matter *why* he is they way he is because that is his issue to deal with. Her issue to deal with is whether she can accept him the way he is. Take all the reasons, justifications, rationalizations, and excuses away, and you are left with a person who does not meet your needs as a partner. That's the bottom line. It took me till my mid-forties to learn that lesson. I hope she learns it sooner. I hope you do, too.
Life is much too short to spend it wanting something different and waiting to get it.
L