Have you ever heard of intermittent reinforcement? There's a good explanation at this link. The link is about relationships with people who have personality disorders, but I think the same things apply to relationships with addicts or alcoholics. Basically, the idea is that when a reward (in this case, kind behavior from a husband) is unpredictable, we can get stuck trying and trying to figure out how to get the reward. I think scientists came up with this idea after doing studies on animals in different situations--some got food every time they pressed a button, some only got food every once in a while when they pushed the button, and some never got food when they pushed the button. The ones that always got food when they pushed the button only pushed when they were hungry, the ones that never got food gave up, but the ones who got food at random kept pushing and pushing hoping for the payoff.
Out of the FOG - Intermittent Reinforcement