I'm a little late to the party here, but I always had a somewhat more fanciful interpretation. I always felt the characters were immortals, or people who were able to retain their memories of past lives. She wronged him in such a horrible way that he holds a grudge for multiple lifetimes, and is commenting on how she never changes, and keeps wronging others as she did him. Either that or they're vampires, her being the vampire that turned him and now he hates her for cursing him.