"When considering a new relationship of any kind, practice the Rule of Threes regarding the claims and promises a person makes, and the responsibilities he or she has. Make the Rule of Three your personal policy. One lie, one broken promise, or a single neglected responsibility may be a misunderstanding. Two may involve a serious mistake. But three lies says you're dealing with a liar, and deceit is the linchpin of conscienceless behavior. Cut your losses and get out as soon as you can. Leaving, though it may be hard, will be easier now than later, and less costly.
Do not give your money, work, secrets, or affection to a three-timer. Your valuable gifts will be wasted."
Dr. Martha Stout, PhD Author: The Sociopath Next Door