Can you ask her if instead of being "assigned" that you are able to meet with at least 2 potential new TT's? That would be worth bringing up.

I agree that she may have been actively blocking your attachment so that you wouldn't be as hurt when she left. Not because she didn't care, she probably didn't want to cause any harm.

This could be a positive development--a chance to find that better fit. So sorry though, it is still a loss.