The fact that there was no revenge in this film...
... as well as the fact that the perpetrator towards the end even attempted to appear somewhat sympathetic, although it could just be a mere condition of his taking over, rather than facing any kind of real retaliation and punishment for his deed (and he even appeared to be somewhat normal middle aged man as opposed to an overblown Max Cady-type of violent sexual psychopath)...
Is that a comment made by the filmmakers that as horrible a deed as it is indeed, there's nothing too wrong with either forgiveness or moving on, and that violent "I Spit on Your Grave"-type of retributional revenge isn't going to help much if at all?
And how come even the woman who was his victim felt some sorrow for him towards the end when he was dying and was even in a way desperate for an ambulance to arrive and save him, and even begged her teacher husband not to hurt him in return?