ERRARE HUMANUM EST. To err is human (everybody makes mistakes). Some of us make mistakes every time we open our mouth and some are capable of making mistakes even before they open their mouth.
It is sad if the same thing happens to us as to what happened to that famous king who people played a trick on and made an invisible suit for him, which only special people could see. Then the emperor put on the invisible suit and went out naked for a walk in the village. All of his nobles and the people from the village did not have the courage to tell him that he was naked and so they paid him compliments and then laughed behind his back… until a child came and told him that he was naked.
We cannot allow the same thing to happen to those who are close to us. If they do something wrong and we know it, we have to tell them sincerely to their faces. For their sake.