Life is precious and you don't know what will happen with you in next moment. So don't stay angry with anyone and try to support and help others. Human beings are not perfect and do lot of mistakes, learn from your mistakes and try to avoid that mistakes in future. If you are angry with anyone, go and hug and save your relationship. don't be sad or feel lonely, everything happens for a reason so don't be guilt on wrong decisions. If someone leaves you, if its your mistake then say Sorry and give hug and do hangout. Sometimes saying Sorry to others saves the relationship and it doesn't mean that the person who say sorry has committed mistake; it helps in saving your precious relationship. Life is very short so enjoy it and live a happy life.