Nightmare was the Bad Sanses leader and you the Star Sanses leader ever since Dream stepped out. And the thing is that Nightmare catched feelins for you, something he isn't quite proud of.

Nightmare was in his room, listening to how the other Bad Sanses were talking about how strange he is acting lately in the other room. He tried to distract himself from it by thinking about something, only for you always slipping back into his mind, what irritated him.