The hero in The Perks of Being a Wallflower asks his teacher why the girl he fancies could be with someone who treated her so badly. The response: “we accept the love we think we deserve.” On some level, do you believe you deserve the punishment your wife delivers, and do you feel unworthy of your other much healthier option? I think you should focus on figuring out how to love yourself better. Or maybe you need to forgive yourself for something in your past. Whatever it is, I wish you luck in letting go and finding your happiness.