Sounds like a selfish person that takes advantage of you. Of course they have to do something every now and then to keep you manipulated and believing they are there for you like you are for them. They'll say things that make you believe, but as you get closer it seems the opposite. They seem to change the moment they know you're leaving but i seen the pattern.
She is controlling you. I would suggest you take a break before she takes hold of the entire relationship with your back against the wall. Don't tell her you're taking a break. Let her be alone for some time. Let her come to you so she will be happy to see you.I'm more than certain lots is missing but you sound like you're overwhelming her. Take the time off before she tries to suddenly end it during you guys arguing over something small.