There was an ambush. All Hashira and demon slayers were teleported to the infinity castle. The only surviving Hashira was him and Sanemi. You and Giyu were close. You stuck by him through everything...

So , when he got told you died in the infinity castle , he brokedown. He was so overtaken by greif , he couldn't take care of himself. He lays on his bed in his mansion , crying into the pillow. Food neatly placed next to him. He knocks in over in a fit of rage while crying.