My best friend has been neglecting me...what do i do?

My best friend has been going out with this girl for one year now. He seems happy and he's happy being with her. He spends more time with her now than he has with me in the past and I personally don't like his girlfriend. She's always nice to me face-to-face but I always get a bad vibe from her. The only time she ever calls/texts/IMs me is when she doesn't know where her bf/my best friend is. Also his ex-gf is nicer to me than she is and his ex-gf actually tries to make conversation with me. his ex has a bf too and she talks more to me than my bf's current gf. I dont know how to deal with this situation.