Damn, Koyori's sis from work is at a 25-years married level of insight into relationships. She pretty much drove their whole thing home and keep pushing it forward while solving all the problems. The real hero of the story.
Koyori is sweet with all the worry, but if it was me, being driven hard at work, even coming home to a snack and a note would give me +20 to energy, let alone being able to cuddle together and just chill. That's the best thing to do when you are mentally exhausted (other than sleep that is).
And finally moving in together (hopefully), took them long enough. Should have started planning for this the moment they knew she will be moving to a different building. They obviously value their time together over their time alone.