@Qelix @flannan
I agree with your points. She is bounded to church and the next hero they will find for her. Her being duke's daughter only adds weight to such a decision. This is a rare occasion I get the MC's inaction. It's rare that this is being portrayed in novels, because it's usually dense MC which is dense for the sake of denseness, without any normal reason. So far she is not worthy of the huge risk of being 'erased' as the MC called it.
Do we know she has without doubt feelings for MC? To such an extent? Friend, lover, first infatuation, someone to tease? She patiently waited for Hero to fail, but didn't actively help MC. She will be there, having a fun time for a month, but in the end, she would still have bound to the church and next chosen hero. She cames with too many things attached to take such action lightly. Problem is that she doesn't act aware of such things, which is the worst behavior.
@D-mann9000 @sjmcc13
She was, but think about it a bit more, she only talked about it but did nothing with the hero. Now think about church and her father, that's some heavyweight looming behind her back. I don't think it's wise for him to start a romantic relationship with her, or he might end up dead if he mishandles the situation. Unless she is totally sure and back that decision, going against a church and the duke, this would end up in failure when she drops out from this out of fear or obligations.