What did she say for him to stop having thoughts of killing her.

I think she nodded? Like yes, they'll be together forever. There's an untranslated suffix/bit by her head that probably would have provided clarity here and I think the two (( below are meant to indicate movement, i.e. a nod.

nah she didn’t say anything, and he liked the reaction of her not confirming it anyways

oh nvm by context it seems she did say actually nod