George-
Being that you two are engaged, I would think that she must have considered marrying you at one time. The actions that you describe are consistent with her changing her mind.
For your future peace of mind, I would talk to her about how you perceive her actions and ask if there are any reasons for this behavior. Ask her what she sees as the future for the two of you. (I think that it would be prudent to have a list of questions that you want to ask her. I would make this a mental list. So think about this before you go to the OK Corral. Listen to her. Ask her to clarify anything that is not clear. But do not dispute with her. Do not try to change her mind. This is an information gathering mission. It is not one to restore the relationship. {Theme music from Mission Impossible is playing in the background.} She may not give you an honest answer, but I suspect she may not have the guts to break off the relationship. Or she might not want to deal with the guilt of terminating the relationship. Therefore, she is putting the ball in your court.
There must be 50 ways to leave your lover.
I can be empathetic here, George. I have recently lived thru this. You can, too. If the pain doesn't kill you, it will certainly make you stronger.
For your sake, I'm hoping that maybe she is having chronic PMS, but I seriously doubt it.
Life goes on. May GOD comfort you in your time of loss.
JayR