Husband

My husband and I have been married for almost 13 years. He’s a great dad and husband but he has this bad habit of looking at YouTube videos of girls with big asses. I totally dislike and I don’t know how to get him to stop. He says it’s normal and all that all men sit it, but it’s getting to the point where if I catch him it really bothers me and I get hurt by it and I just can’t it take it. Every time I find out he’s been doing we end up in huge fight and it makes me want to get a divorce. But then I get over it and then I don’t. Help I don’t know what to do?