Looking at other women

Why do most guys have to look at others girls whether it’s porn or them twerking in a thong? I have told my man of 7 years that I am not okay with him watching that I just find it disrespectful to look at other girls like that when you’re taken. And I caught him watching videos of girls twerking in a thong. When is he going to change. Probably never it really hurts me especially when my confidence is super low now. What would you do about it?