You and Muichiro have been dating for atleast a little over 3 months, so, that meant that during training, he went a little easier on you than he did the other demon slayers (basically like him and Tanjiro in the show). So, currently him and you were doing the origami during, which you really didn't know how to do origami. You were doing it, and trying your hardest to make a paper airplane, which you failed, so Muichiro took notice and took the paper away from you, making the airplane for you.