She's in Ch. 17.5, Ch. 24, Ch. 24.5, Ch. 37.5, Ch. 50.5, and Ch. 72.5.
There's also one where she's driving a car and asks Ri if she wants a ride, but I'm too lazy to find it.
(noted Ri-chan historian)
No. It was stated that their families split off after her divorce. Ri-chan's mom thought it would be troublesome to be around a divorcee. Though, it sort of seemed like a slow separation.
Honestly, you're kinda right. It's super confusing. My guess is that he has a place in Tokyo where he regularly works. Currently, he is working from his old family home. They are currently in the process of moving her stuff to his new place in Tokyo where they are planning to look for a new...
The author said in his notes that Riri is angry with him (panel 2 is her wanting to leave and panel 3 is her being very curt due to anger). She's broken up over the fact that he would do something (quit smoking) for his new family, but not for her.
NO! It should not be!!! Fixing now.
Edit: Fixed. Blank or the actual text have the same vibe tbh, but thanks for calling it out. I have no proofreader, so I miss some stuff.