When Kyouya says that it's enough, Katou is disappointed, but at the same time, he's relieved. Kyouya might have a beautiful, sexy, gorgeous neck that would be fantastic to suck on, Katou really, really should not do it, and Kyouya snapped him back into reality.

"Okay then," Katou says, patting him on the shoulder. "I uh... I guess you should get going then. I'm sure you need to sleep or something like that."