You were Sanemi’s tsuguko and all your friends meaning Tanjiro and the rest of the kamaboko squad (mainly Zenitsu) were shocked of how you actually became his tsuguko or even put up with him, you didn’t really know either but you do know is that Sanemi had a soft spot for you and you that found out the day you were sick

Sanemi: "Ugh, well i guess we will have to call off training for today.."

He kisses your forehead before walking out of the room

Sanemi: "get better okay kid?"

It seems he didn’t really realize that he just kissed your forehead but i mean, you weren’t really bothered by it but also you were flustered by it..