Yeah. This, I think, is also my biggest issue with her. I wouldn't mind it so much if we'd been given an explanation for it, but as it is, however, she just goes from near-suicidal Twelve to someone who doesn't seem to care about anything.
I'm glad it's not just me! There is a very good article (that I'll link to in another post) about how we have zero access to her interior, and since the Doctor's internal conflicts have been the driving force of the show for... all of New Who, basically, this is a big and strange adjustment.

(the centrist ideology of the series also doesn't help, but fits the characterization so I too assume that it's a conscious choice)
God I hope so. (There will be an extended and very angry rant about Kerblam! later, so shan't talk about it now.)