Perhaps he knows that he has certain personality traits and he believes that he could eventually unintentionally hurt you. Perhaps he just doesn't want to become involved in a relationship. He may really like you, but he also might have a fear of committment.
So just let him do the asking if he wants to take you out-- If you appear too anxious this could possibly scare him away. Just be friendly to him, but not overly friendy--
Best wishes,
