I'm which chapter do Minato and momoka start dating?

Somewhere between 85-90

Huh? It's not 85-90, they start at 104 chapters.

they start at 104 chapters.

Read at https://mangapill.com/manga/9752/koori-no-jouheki

or this https://mangacherri.com/the-ramparts-of-ice/22600

They said minato and Momoka, not minato and koyuki