Beyond Selidor

You are absolutely spot on — I think one of my least favourite tropes is the idea that characters (especially misfit/damaged/traumatised characters who have found a home and a family in each other) spend an entire story building connections, saving themselves, the world and each other ... and then their 'reward' is to separate from one another forever and leave the world/city/home they've built so painstakingly.

Your 'temporary parting of the ways' is basically my headcanon for the series. I am in no doubt that Inej uses Ketterdam as a base, and that Kaz, Jesper and Wylan will stay there. Nina ... is more doubtful. It feels to me that Bardugo is emphatic that Nina's home is in Ravka, and her role is as someone supporting Ravka's political aims and helping the Ravkan leadership achieve them. Whereas I left the Six of Crows duology with the opposite impression: that the duology represented Nina's long, slow realisation that Ravka was behind her, and that she was done with hitching her considerable powers to the Ravkan cause. So in my head Matthias doesn't die, and he and Nina also stay in Ketterdam.