boyfriend with girl best friend

Hello all, I'm in a bit of a rough situation with my so. We go to the same school in the same grade and we've been dating for about a year and a half? And there's a girl he's known about a month longer than he's known me(so about 2 years) who he was friends with. But ever since this school year started back in September, they've grown extremely close. It seems to me she likes him (constantly asking him to hang out, always talking about him, always talking to him and texting him. Basically, he's her world) The whole school thinks they are dating, he's gotten a lot less affectionate with me, he ignores me around her and hangs out with her more than me, and he got her a christmas present and a birthday present and I got nothing (except some flowers on my birthday a few months ago and a promise for more) and our birthdays are a few days apart. He's lied to me multiple tomes about when he was with her, and overall it all just makes me really uncomfortable. The closer they get, the farther apart we get. Whenever I try to talk to him about it he just dismisses put and says I'm jealous or that it's normal for guys to have female friends like that and in the end I end up apologizing for bringing it up. What should I do? Note: she's in our school and in our grade and all my friends think it's weird too. People come up to me in the bathroom and ask when him and I broke up and when they got together :/