I agree...

It sounds like the relationship hasn't been working properly for a while, for her at least (even if you thought it was ok like that, she probably didn't!)

I was going to say just walking out with all her stuff is pretty cowardly, but then you said you told her to pick her stuff up - which maybe gave her the reason to do what she already wanted to do, but was probably too scared to.

I've been in a similar situation (the girls situation!) and to be honest it sounds like she has 'left' emotionally a long time ago, and has only just had the guts to do it physically. I wouldn't hold out much hope of the two of you working things out.