I would giver her space. I've said the same things because I needed space and I felt trapped. Nothing to do with you! But maybe she HAS met somebody else, or SEEN somebody else that she would be interested in. Give her, her space. That will give her time to think, and time to see how much she does love and appreciate you.
I don't know you or her so don't take this the wrong way. I could be completely wrong. But, if it were me, I would definately be wondering if see has met or is interested in someone else. Sorry.
Well, a couple of ideas. Ask her to go on a weekend getaway together and make it extra special. See if you can put the romance and joy and discovery back in the relationship. If she will go, that would be a second chance.
If she won't go, see if she will go into couples counseling to see if there is an issue that can be solved.
If she won't do either, then I would just back off--tell her to come if she misses you, or stay away if she doesn't. If she does miss you, she will recognize it and be the one pushing to get things back together. If she lets you go-- there is nothing you can do but move on.