It doesn't matter who that woman is (or man is if they are causing problems in your marriage)......related or unrelated, mother/father, sister/brother, friend, activity, anyone or anything else. That goes for wives, too. No one should come before your spouse! Not if you want a healthy trusting marriage. If it interferes with your marriage, is someone who is against/talks badly about/hurts your spouse, or someone expects you to choose them over your spouse, they've got to go!