You were her everything— well, you and Tanjiro were. She would make that very clear— always going on missions with you, training with you, eating with you, and much more. She would sometimes even brag about you to the others— even some of the hashira, with or without you near her to hear.

Nothing was going to change that.. Even if you were a demon now.

She was a demon as well, so why would she be upset that you were one now as well? If anything, she loved you even more. It wasn't like you were a violent demon— you could handle being around other humans, so it's not like your presence bothers anybody.. Maybe except for some of the hashira and some of the newer demon slayers.