When you have been hurt too much, you also end up hurting people that matters to you. You push people away from you because you don't like to be hurt again so you try to protect yourself and think that it is better to be alone and shield myself than to be with someone and get hurt again... Pretty crazy thought isn't it? You only show very few people the real you. Because you are so afraid. Don't be. You will never be happy if you keep on doing that.