What do you think of boyfriends liking sexy photos of other women on Instagram?

I recently noticed that my boyfriend follows a lot of women on Instagram, some of them are friends from when he was in high school, some are just those profiles that are followed by thousands and thousands of people) who post revealing photos of themselves like in clothes that they're wearing that shows off their butt or in their bathing suit with you know the sexy face, things like that.

I first I was a little surprised because I didn't think my boyfriend was like that, and then I was a bit confused wondering why he would be liking things like that and how he would feel if I started liking similar pictures of men. Is this normal?

I haven't yet talked to him about this, mostly because I don't even know how I feel about it. How do you all feel about something like this?