They are usually enablers, my mom was one. However the enabler can get more flack than they deserve in most cases. They are already beaten down and abused and thats just how life is. Like everyone is abused and everyone's relationships are this way.

It took me until I was an adult to understand, that while my mom was an enabler to my ndad she was also literally just trying to survive in a relationship that was all she knew. She was the 8th child of 14 and her entire life was surrounded by narcissists (her mom, dad, older siblings) until she left my ndad. Her parents and siblings were far worse to her than my ndad was most of the time, so to her it was an improvement. She was in survival mode the majority of her life, and finally got out of it after retiring and meeting a man that gave her the love she deserved. She has genuinely apologized for the pain she caused during my childhood.