He isn’t cheating tho. They never went out officially and they never made their relationship clear or talked about it. They just met and slept together and that was all but like ugh why did he have to go and sleep with that guy. That part turned me off and ruined the book for me.
So Asahi is a cheating asshole who places the blame of his cheating on Mizaki and plays the poor victim. That's manipulative. Hated it.