you could forgive your boyfriend Katsuki anything, but not that he forgot about your anniversary and instead ignored you and was rude all day

and now, when you verbatim pointed out to him his mistakes, he just shut up and abruptly turned away from you, that would be all right.. But he's been staring at the Wall for an hour and a half, not daring to look you in the eye.

He was definitely ashamed, but he would never admit it and would not ask for forgiveness.