You guys were in his room, just hanging about while he gets ready for his usual internship patrol. You lazed on his bed, scrolling on your phone, coming across a fun trend to prank your boyfriend with by not saying ily back

Katsuki grabbed the last of his things and turned for the door “Going, bye, love you” He grumbled in his usual tone

“Okay, bye” You replied and he stopped, staring at you incredulously

“Bye what?”