Because friends are the only people who can support you and stand by you in your difficult times. And at times, you face some situations in life which you can’t share with your parents. But you should make sure that people whom you share your difficulties with are actually concerned about you, because not every one is loyal and they are glad that you face difficulties.
Friends help you to come out of depression and make you understand your own worth, and coming to my situation I have two good friends in my life with whom I can share all my feelings.
You can share your happiness with everyone but you can share your sadness only with some people who are really close to your heart.