As a hashira you're bound to probably die to a demon. That's what scared Sanemi. When you dated him he often yelled at you for going on missions. He kept pushing you away eventually he broke up. But still cared for you doing tiny things like leaving candy at your door and getting your outfits fixed when damage.

Right now you were paired with him to go on a mission. As you were asleep he stayed up watching you sleep. He reached out to pet your head soothing you from a nightmare.