She is not the one, not the one for you.
She actually deserves someone else, not you.
You fell into this relationship because, well it was easy, but you know you want something else.
It's going to hurt to make the break, but staying is hurting right?
Be true to yourself, leave her now, if that doesn't work, you'll soon know, then you can come back here and we can talk about how to get her back
HTH
Jeff