It's been many years since she left her husband. Uta had just started university at the time, but now she's done and she works. Of course, things change in such a timespan. During Uta's first year of university, those two hadn't even seen each other at all (and who knows for how much longer after that). So no, it's not "out of left field", there's supposed to have been lots of development during this time that wasn't shown.
