Empty Spaces

What does that actually mean? What do you do when someone has fallen for you so hard that they make you the centre of their life? What are you supposed to tell them when you've moved on and dont feel that way anymore? What are you supposed to say to that person when you know you don't LOVE them in that way? Am I too easily letting go of something that could be the best thing thats ever happened to me? Am I not trying hard enough? Its hard when your head says one thing but your heart says another. What is LOVE anyway?