Half naked women on IG

How do you guys feel about your partner looking at photos of “IG baddies” who are shaking their butts/half naked? I told my husband numerous times this makes me feel insecure and hurts my feelings. And I just found out last night he’s still doing this. He said he’s sorry and he’ll never do it again and that he’s dumb but he always says this when I find out. He said maybe it’s just a guy thing. Should I just let him sexualize other women or are my feelings valid?