When you are with someone for a long time, you take on some of their traits. If they hate themselves, they begin to hate you because you are a mirror of the things in themselves that they don’t like. Find your definition of who you are in the gospel of Christ. Be who God has elected you to be in His sovereign will. Let Him mold you and define you so that the person you are with will see Him instead of the sinful things of themselves in you. They will leave you, or repent and draw near to God and you.