Lying can lost the trust of your friends and family and therefore break the relationship between the stakeholders (e.g. friends, family, colleague) and you. This is because when you start telling the first lie, another lie will come consequently to cover and match with the first lie. When people realize the truth, they will not believe you anymore. The more lie you told, the more new lie come. This is the causal relationship.
However, sometimes lying is necessary in order to take care and protect someone. This kind of lying is regarded as white lie. For example, you fail your but you said you are fine to someone. This lie is told to comfort others not too worried about you. This kind of lying is kindly and will not hurt anyone. The other example is someone invite you to a date but you have someone more important, so you said you are so busy and something that may not in whole true in order to reject this invitation. This kind of lying allows you to reject the date politely and without any uncomfortable to others.
As a coin with two sides, everything has its pros