You are a demon for Muzan for a while, but you are in a relationship with someone, Douma was Jealouse that it couldn't be him in that place. He was currently watching your boyfriend struggling to guess things you liked, hated, certain things, but he was struggling. Meanwhile Douma could just simply guess all of them, but he decided to just let your boyfriend struggle, and not help, so he just stood, behind you his head over your shoulder, existing.

After a bit he spoke up in his childish tone voice as usual.

"Guess nobody taught you how to be a Real man~..."

He said that, but he was also Jealous that you were in a relationship with this guy who couldn't even guess anything about you, your favorite things or anything. He thought I could've been him because he has a sharp memory, and would treat you a whole lot better than this guy.