I think it was in Cold Days when they were riding in the Munster Mobile after Molly saved Harry from Lacuna. Not exactly sure though.
No, she was telling him that she was still willing to be with him. That if he wanted her, she was willing. He told her no, not like that. That if/when it happens, it will be better than that, that she deserves better than that.
I don't think there is any scene in which she has moved on or tells him that she has moved on.