Time or Times Up

How long do you give someone? Is there a time limit to realize true feelings or are true feelings truly instant? How long until you get fed up with waiting? How much time do you allow to pass before you realize that it is time to move on? I have a heart that can't let go so I am apparently not the one to answer these questions. I get advice from others and they tell me that one day I will wake up and be over it all and that's when I will know that I moved on. What if that day never comes along? What if I can never let go? Through the fact that I don't truly want to move on won't I never move on? I wake up thinking about it, go to sleep thinking about it and exactly what point is it going to leave my mind? I dream about it, see it at work, think about it every song I hear on the radio, every movie that is released? Has it just become a habit and obsession and that is what I am not willing to let go of? Or is it true feelings that can't be erased because once your heart has been touched by someone, you can never go back?