Okay that ending is something straight out of a hentai. The girls can't brush that off as a punishment game or anything. At this point they both better commitment to a polygamous relationship or else the MC can never get married 😂.
"we've been cosplaying all day; you have to too"
The MC had a freaking globe on his head all day. I don't think that's how he usually looks.
Also I love the sequences this chapter with classmate calling out Amane's special treatment toward the MC and jealousy over the kid not recognizing her cosplay was hilarious.