If your boyfriend lies and breaks promises, you might wonder whether the relationship is worth the effort. One out of five daily interactions contains a lie, according to the Psychology Today article, “Why We Lie and How to Stop.” You would hope for a better track record from your boyfriend, but you know he doesn't always tell the truth. Understanding why he lies and breaks promises might help you create a more honest relationship.

Value Trust

Explain to your boyfriend how his behavior hurts. He might be amazed to discover that you don’t trust him, especially if his motivation for lying was to make you happy or spare your feelings. Perhaps he makes promises to pacify you. He says he will watch the kids so that you can rest -- but then he doesn't. Explain how his dishonesty affects your relationship. Express your personal perspective on honesty. Make sure that your actions match your words.

Discovering Motivation

Ask your boyfriend why he lies. He might lie to avoid your anger and judgment when he does something you won’t like, according to Margaret Paul, a psychologist, in the YourTango.com article, “Why Did He Lie to Me?” He might also lie to make himself look better to you, according to research from psychologist Bella M. DePaulo in the Reader’s Digest article, “7 Lies Men Tell Women.” For example, he tells you how close he is to a promotion that never materializes. The lie makes him look good -- at the time.

Importance of Honesty

Take a pledge that you will not lie to each other -- eliminating even white lies that seem harmless but destroy trust. For example, he says he will take you out. He calls at the last minute to say he must work late, but you can hear barroom noise in the background. Ask him to only make promises he can keep, advises Jeanette Raymond, a psychologist, in the YourTango.com article, “Why Does Your Partner Always Break Promises?”

Rebuilding Trust

If your boyfriend has created a pattern of lies and broken promises, it can take time to rebuild trust and develop a habit of honesty. If he slips, remind him that you both pledged to be honest. Ask him why he lied. Remind him that he must be truthful to remain in a relationship with you. Hold up your end of the bargain. Refrain from angry outbursts and judgment when he tells you the truth. By supporting each other, you can develop an honest relationship built on trust.