Here is my advice to you-
This girl you are dealing with is very fickle. She doesn't know WHAT she wants. She doesnt want to ruin a relationship she's worked on for nearly 2 years...
And Tanya says never believe a girl when she says she's going to break up with her bf. Because she's not actually going to.
So, give this girl an ultimatum. Tell her, "Sweetie, I want to be with you but I'm tired of waiting on you to make a decision on who you love. I want to be with you, so you need to make a decision now."
If she still can't decide, you need to leave her for awhile until she knows what she wants.