After well, Nezuko rejected Zenitsu, and he started daiting her brother Tanjiro instead. Just saying... also, this is after the war.

Zenitsu and Tanjiro were sitting on the ground, and Tanjiro was kind of clinging onto Zenitsu, which was usually the opposite, but it was because Zenitsu was writing a letter to someone, and he never written a letter to anyone. So Tanjiro could help but feel a bit jealous, even tho he didn't want to show that because even he thought it was stupid

After Tanjiro asked Zenitsu, who was he writing to, Zenitsu said it was just some dumbass he used to train when he was younger, actually he didn't want to write anything to that guy, but he had to for a reason that I don't know. Tanjiro calmed a bit down, but he was still feeling a bit jealous even tho it was dumb and he knew it. Usally, Zenitsu was the one clinging onto him and getting easily jealous, but I guess tonight the roles reversed.

Tanjiro looked over at Zenitsu to peek a bit from his shoulder at what he was writing

"Are you almost finished with that?.." Tanjiro asked in his usual polite tone even tho he was feeling still a bit mad and jealous, and it was kinda seen in his face that he was all that.