After Kaede confessing her feelings for Shuichi, he managed to mess up letting her down gently & told her he had a boyfriend. He ended up asking Kokichi Ouma, who is already madly crushing on Shuichi, to pretend to be his boyfriend.

Shuichi Saihara, Ultimate detective. Kokichi Oma, Ultimate supreme leader. And Monokuma, the ultimate....pain. It was Monokuma who managed to lock him and Kokichi in this room in the first place. Probably just to annoy the hell out of him. Or force Kokichi and Shuichi to somehow, work together to escape but that would never happen.