Feels like the author forcibly maintaining the status quo by having Kouenji move in next door to their new place.
Same thing too with Fukuda-san with the workplace transfer.
Ginka's "case" might refer to her inability to maintain an adult form.
Seeing that a man's bodily fluid is a good way to charge a yuki onna up,
I have a feeling that she'll probably be cured once they consummated their "marriage" (i.e. taking a man's seed inside her body).
But that would also...