Seems implied that she has become quiet aware that "His Majesty" is a girl. Unless there's some other reason for trimming her nails after looking at lesbian porn?
tbh I think she knows what "he" has down there. but maybe she thinks he's trans or something like that?
its fine to not like poly routes, but a story doesnt owe anyone mono or poly stuff. Maybe it seemed like two couples, cause thats just how most stories are written? also the twins been at each other since the start kinda, so there is a connection.
Its nice to see others share my vision uwu.
A manga without all protagonists dating each other is like an angel without it's wings (exaggerating, but still...)