I get jealous.. help

So it’s not that I don’t trust him, it’s my own insecurities. He is a truly amazing guy, honestly. He’s perfect. He honestly believes I’m so perfect and the most amazing person ever, and he makes sure me and everybody else knows it. But when a pretty girl walks by, I see him look at her for a second as she passes by in the hall, not checking her out, just a glance. I do it too, it’s nothing at all, just when I walk I look around. It’s not that my eyes get pulled towards somebody, it’s just that I happen to look. And he says the same thing happens with him, but I see him look at girls. It bugs me, he says he finds absolutely none of them pretty whatsoever, but he said they can look good if they wear a nice dress or something like that. I’ve been hurt in the past, and I handle everything badly so when something happens and he fucks up and he knows he fucked up with something like that, I get really quiet and upset. I know there’s gonna be girls in his life that he talks to, but he’s mine. And I don’t want him to look at any other girl and see beauty, I’m just scared