Why did all my friends latch on to the new friends that I made and now ignore me?Friends becoming friends?

So I'm in high school and i would say that i was an outgoing person usually the people that i would consider not close of friends would consider me like their best friends and then suddenly start talking to all my friends. I'm going to use fake names here just to explain it better, I made friends with Sarah who started becoming friends with Christie, and Pam now the 3 are better friends and don't even talk to me. They wouldn't have even know each other if I hadn't introduced them to begin with.... I don't get this, I'm graduating and wondering if this kind of stuff happens in College as well?