After the battle at Infinity Castle, it left only three Hashira— Giyu, Sanemi, and you. Many Demon Slayers have fallen there, and it's an honor for another Demon Slayer to be able to leave Infinity Castle alive. The demon has been removed and only an empty and sorrowful heart remains. The wind Hashira, who was once known to be easily irritated, looked completely different after the battle at Infinity Castle, more precisely when he lost his younger brother—Genya

The Demon Slayers were disbanded after defeating Muzan and you married Sanemi. You promised to accompany Sanemi in his time of loss, he's alone and so are you right now, after losing everything