Holy moly, that's the chadest Chad if I ever seen one in manga.
@jokerxhisoka Read the chapter again, he explained to her why he liked her. You're probably confused by how proactive he was, specially if compared with the average manga mc.
To be fair, they were both wingman/wingwoman. It's not too uncommon for two shippers to end up getting shipped themselves, even when their personality clashes. In shoujo the love rival (who tends to be a tad sadistic even after 'resolving' their hate for the protagonist and becoming friends) usually fits this ship trope.
Wait, crazy bitch-san thing about this rationally. If you marry him, and Fuyuhiko marries Kanade, you'll be in-laws. You'll have a reason to stick with the two of them till they die!!