Help, if you can be bothered - ^

[doc_bean]

I dont want to be more than friends with her.

But i dont think that this is starting a year of a close working relationship very well.

EDIT: Do i care about the why? Yes. i want to know why. I hate not knowing why something happened.

Well, don't feel bitter about it, she probably didn't know how to tell you she was going with someone else, or, she was actually telling the truth and didn't want to go but then the guy she has a crush on asked her and she just couldn't refuse.

Honestly, don't make it about you, what she said and why she said it probably has more to do with her and her situation than with you.

Perhaps you can ask her why, but then that would probably lead to uncomfortable situations. If you just want her as a friend you should be able to shrug this off. Friends shouldn't threat eachother like crap, but occasionally, when something shitty does happen, it can be better to just let it slide.

Besides, this is a dating occasion here, you shouldn't expect priority as a friend over a potential lover.

EDIT: What I would do is probably mention it to her and then tell her it's no big deal she's going with someone else, that I really did ask *just* as a friend and that I'm happy she found someone. All said with a dose of humour so it doesn't sound pathetic.
Of course, this only applies if you just want to be friends. Most advice here seems to be focused on her being a love interest.