I'm halfway there. You are right and...she knows he knows, so saying sorry would have moved things, at least a minimum.
But from another pov, replying like that is still kinda lame; I mean, if you want to cut ties with everything fine, but at the same time he could have at least asked like "why do you want to trade numbers if you don't think of me as a friend?" thus sparkling discussion.
Also ok being dense, but you can't reply like that and then wonder why she changed idea and doesn't want you to go with her anymore 😅