Bf wallpaper bothering me...

My bf has a picture of Kourtney Kardashian as his wallpaper on his phone. He used to have a picture of his mom as his background but he recently changed it to Kourtney. At first when i saw it did not bother me at all. I was just like ehhh she just a celebrity. But now it kind of bugs me. I "jokely" told him that if he's gonna have a girl as his back ground it should be me. Idk why his wallpaper bothers me. I asked him to change it to anything else but what he has and hes just like "why does it bother u its not like im ever gonna meet her". It didnt bother me at first but now it does. Maybe because the pic is her in lingerie. Idk am i over reacting. I know its not a big deal but it bothers me Everytime i see his phone screen.