Don't let people's behavior keep you from doing what you know is right

I'm dealing with a situation right now where someone near and dear to me is acting very far and unloving. This has been an on-going situation stemming back decades. Things will go smooth--until that person determines they shouldn't Everything's fine, till he decides it's not. Then he turns into a hateful, horrible controlling monster. Are there mitigating factors? Meh. Sure. Crazy schedule, exhaustion, lack of family time, stress at work, smoking. Does that excuse it? No. Most of the factors he has no control over. But he does control how he acts.  Don't let people's attitude and behavior keep you from doing what you know is right