I think Eva was supposed to marry Henry, only a goldspinning miller’s daughter was a better option. Somewhere inbetween I would like to think that Eva got insight on how horrible she treated Cora and what that did to her, repented and changed her ways. For heartless Cora however, such a deed would never be enough, just like Snowwhite can say sorry to Regina for a thousand times about Daniel, and she still won’t forgive her.