Bf looking at other girls...

How do you ladies or gents feel when your significant other looks at other girls in my case that are extremely pretty and have a really nice body? I am very self conscious and I hate that feeling when my bf just stares blank at other girls that I know for sure look better than me. Worse feeling is that he doesn't look at me like that. When he notices that I have seen him staring he just looks away and try's to be sweet with me.