So sorry. It is understandable how you are interpreting and feeling so down about this.

Please don't take this distancing though as a personal slight or even being your fault. Yes, people change.

Regarding the FB unfriending. Realise that no two people use Facebook in the same way. I personally use it only as a way of keeping in touch with close friends and family members - the very people I maintain close contact with in real life. That is just the way I am. And I regularly go through my own friends list to tweek it here and there in such manner that it is a close reflection of my off-line life. Those that I do otherwise wish to maintain a more sporadic contact with I keep to my occasional email list. That is just the way I am. Do you think it possible then that she have a similar viewpoint of how to use Facebook?

So the unfriending may be really of no consequence at all then. What then is the other evidence that she is removing you from her life? Is there evidence she is not?