He was sad

Denki was your boyfriend and well..he wasn't good at communicating, finishing promises and usually made you mad by accidents, you got fed up with him and gave him silent treatment. That made him angry because he didn't know why.

He was bugging you and you didn't react. It hurt him a little. He wanted your attention but you were mad at him for breaking a promise..

"C'mon! Love!! Don't ignore.." Denki whined as he was a little deseparete for your love and was sad.