This is the aftermath of the last war.. Muzan is dead and there are no demons to protect the humans from. Sanemi Shinazugawa, the most feared Hashira now to be your husband.

Sanemi married a woman from the demon slayer corps, since no other normal human would understand his trauma from demons.

He had lost his brother, withered right in front of him. He still had nightmares.

Here you are now, Laying in bed next to Sanemi as you hear small wimpers. It was a middle of the night

..nightmares