Am I insecure or is this disrespectful?

My boyfriend of 8 years likes girls bikini and ass pictures on instagram. i ask him why he does it and gives me different answers. i’m not sure if im not sexy enough for him or no matter what i do this is something men will continue doing? am i being insecure or is this technically normal for this day in age?
Am I insecure or is this disrespectful?
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