Also, to allow hurt to stay alive in the memory is just like programming our own karma..
IMHO, to learn, forgive, forget and then let go and proceed, is the main way to process energy and to move away from any particular vicious karma circle..
I agree that fear also plays a key role here! The fear of the unknown is what probably makes most people hold on and not let go and sometimes is also what makes them get betrayed over and over again! Maybe not by the same person, but by another person in very similar circumstances!!!
They essentially stay in the same vicious karmic circle...