After they done packing Mumu's things, the power outage suddenly turns on again and Mumu asks SYX what he's thinking. And he said, how to convince Mumu to come to his house. Then, Mumu said, let's go then. (They kissed in the dark though) sorry i don't really remember how they kissed
ahjussi knows what to say at the best of times so i’ll forgive his dry responses