DA22 almost spot on. Yeah, Sonja has an odd way of trying to get her feelings across. It's tough for her, her entire life has been to show strength and not weakness to get ahead. The problem for her, weakness is there. One being how much she still does care for the MC even if not romantically. When they split it was amicable, both characteres being hard headed as they are just saw something like a divorce an unwarranted waste of time. They split and moved on, or are trying at least. No official documentation is going to change that for them.