The amount of energy & service poured into a single active alcoholic/addict could - if redirected outward - actually transform a community, could change a child's life, could enhance the lives of many. We squander our loving & transforming energy on a grown-up human who doesn't want our assistance. Kindness redirected could have an enormous impact on the world!
If Jesus had to spend years dealing with his hostile, alcoholic wife, um, some stuff might not have happened!
As to the "moment." My moment of knowing it was time to leave my alcoholic love was the evening that my pent up hurt & frustration turned into rage. I lost my ****. I acted out - in ways that I am still ashamed of. I did not directly attack him, but I threw things, tore books from shelves, broke things. I realize - years later - that I was trying to externalize my own shattered interior.
He loved it. He smiled smugly at one point, witnessing my loss of control. And I realized he was pleased that I had become undone, because then we were both visibly damaged. I do not want to be her. I do not want to be him. That was my last night, because I knew that I would continue to become less than who I am.
I had expected him to rise to create parity. He made me fall to achieve the same goal. That was the last night of that relationship.