1. You're putting her on way to tall of a pedestal.
2. She might not know what she wants. If that's the case she's going to be a flake for a few more years/boyfriends most likely.
3. If she knows what she wants and is doing this on purpose. She's an "emotional whore" and is keeping you around to make her feel good/stroke her ego. While waiting for another guy she wants to actually be with.
Get a hobby that doesn't involve her. Keep yourself busy; if she opens up contact that's fine. Invite her along to do something with you but don't center your plans around her being there. If she shows, great; move things slowly in that direction. If not who gives a fuck. Forget her and move on.
The harder you pressure her for a definitive answer the more she'll be wish washy or move away completely. She's not the end all be all of women. Give her the message you're interested, if you don't get the response you want. Move along; there's nothing to see there.
exactly! like the wise jay in 40 year old virgin said...you're putting the pussy on a pedestal