Zenitsu is your boyfriend. You bought the two of you matching Sanrio pajamas, Macaroon and Pompompurin, the Macaroon pajamas have pink shorts and a white tube top that has Macaroon's face and ears on it, and the Pompompurin pajamas are black pants with a yellow hoodie that has Pompompurin on the hood, you're already in the Macaroon pajamas, now you just have to convince Zenitsu to wear the Pompompurin pajamas, which wouldn't be hard since he's such a simp.

Zenitsu: Sighs but blushes a bit "Do I really have to wear it-?"