Barring specifics from any source material, this sorta feels like it's reaching a conclusion point.
Her brother has demanded asked that Sorata talk to Miyuki about moving back to Kyoto, and Sorata has seemingly fully internalized that, yes, that's what she probably wants to do--given how much she loves this place, and because of the accumulation of all the moments in time where he feels he just doesn't understand her, and thinks she might actually only be with him out of some obligation to her grandfather.
So over the course of the next ~4 days of this trip, he's going to get "hint after hint" from Miyuki and from her parents that she actually misses Kyoto, and she'll make lots of comments about her grandfather and Sorata will resolve to break off their engagement.
From there, I'm sure it'll end with them together after talking out the massive string of miscommunication between them, with Miyuki reckoning with her inability/reluctance to show her affection for Sorata, and confronting her family/brother over pressuring Sorata into talking Miyuki into going back home and all the "misunderstandings" her brother and Sorata had since he was a child.
Probably a big moment of drama where things almost fall apart, before Miyuki panics and shows what's in her heart at last and they reconcile.
Accuracy aside, that's the vibe I get from everything up to this point.