Why does he always talk about how other girls look?

In an open relationship it's possible to have an understanding that it means nothing if he says his honest thoughts about other girls. That doesn't sound like where you're at here. And usually it's accompanied by compliments to you (if he's being honest about everything with other girls, but not giving you compliments, what does that tell you?). Sounds like he is either EXTREMELY unaware that what he is doing is jerkish, or he just doesn't care about it...or you.

Haha I would do that to my ex but no1 personal though like if we were watching I would be like that chicks hot and she would get a little mad but I would recover by saying but not as hot as you or something along those lines and she wouldn't be mad anymore. lol

My boyfriends says things like that all the time, but I'm pretty sure he's only trying to make me jealous because when I do it back he stops. He always calls me gorgeous, and talks about me to his friends all of the time (his friends tell me lol). Boys need to be constantly reminded that they are loved, and cared for. Speak to him if it bothers you that much, and I'm sure he'll tell you that he loves no one more than you.

(ps my age is wrong I am also under 18 =])

I don't think its that at all. Guys do that to make there girlfriend jealous to get a reaction. If you get real upset look at a other guy and say that guys really hot and see what he says. You are young as like is it's innocent you guys should be fine.