Every relationship is guided by a number of factors that may be perceived subconsciously, but they really matter. These are what make people in any kind of relationship co-exist without much commotion every now and then, or the unnecessary suspicions and weird feelings of betrayal. Talk trust, love, intimacy, and keep the list going. There are some bonding factors which a relationship cannot do without.
Nothing hurts and breaks a relationship as quickly as dishonesty. When trust is lost it motivates behaviors such as criticism, rejection, and jealously.
Honesty and trust are the highest form of intimacy. If you tell a lie once then all your truths can become questionable.