Hahaha... using Kosaki's epically bad cooking as a weapon is so brilliant.
And yeah, of course Raku had to do that. It was his intention all along to reject her in that way, obviously. He has only a handful more to tell as 'dear friends' (I dunno if Haru is counting in that or not, but I am counting her alongside Tsugumi, at the very least) until he's down to the one he truly loves.