Dear Fed-Up,
Believe it or not, I understand. One of my friends in high school acted completely weird whenever we were together, and then normal at every other occasion. I suggest not letting it bug you, because though she is your friend, she's in a changing state. You know, I understand that doesn't make you feel better. But you can decide to change too, if you want. You don't need her in your life if she's just going to mess things up. And, if there comes a time where you just can't handle being without her, then here's what I suggest.
Wait for a period of time, maybe five weeks, and just completely stop talking to her. When she says hi, smile. When she asks a question, answer. But make everything short and sweet, there is no need to be mean. Then, when the time is right, start talking to her. Make a conversation, and then be the first to leave. She needs to know your not clinging anymore, and that she's not a neccesary part of your life. Watch what happens.
Chances are that she'll be more eager to converse with you, and be more willing to hang out. It usually works both ways, because you will have discovered that no, she's not a neccesary object on your path, more just a habbit you've broken. Thank you so much for writing!
Sincerely,
Ask Allie