A similar thing happened to me, although I go to a boarding school, so they had a more difficult time running away, and just started ignoring me. It's really painful when you think you have something wonderful and the other person is simply able to walk away from that, but you should definitely not let it affect your life. I know I'm more paranoid about that situation now than I should be, which has made other relationships (even platonic ones) more difficult, but I think it takes a certain kind of person to do that, and you just have to watch out for that. If someone's cold to other people and nice to you, chances are they'll turn cold to you too...