Unfortunately, you can’t stop a habitual liar. You can’t control another person’s actions. Someone who is a habitual liar has deep-rooted issues. Sometimes the lying can be a clue that there is a more serious problem, such as a personality disorder. There is only so much you can do in this situation, as the person did not become this way overnight, and true changes will have to start with him or her. But there are a few things you can try to minimize lies and hopefully help a habitual liar.
Encourage the person to tell the truth. Explain why telling the truth is important. Mention that people don’t trust or respect liars. Tell him that eventually he will turn people away. Habitual liars tell stories because they need attention. Help him see how self destructive his actions are and that he is pushing away the acceptance he needs and wants.
Confront the person’s lies. Do this when you have proof of the lies. Don’t attack her, but firmly tell her that you know she’s lying. Give reasons, provide evidence and point out the holes in her story. Prepare for her to become defensive and deny any wrongdoing. Be aware that you will have to do this often and possibly for quite a long time. Even if the person admits to one lie, when she is comfortable, she will go back to lying. You’ll win some battles, but not all.
Help the person seek help. Work together to research causes, symptoms and treatment for habitual lying. Seeing a counselor or psychologist may help if the person is willing. If you see that he is trying to help himself, reward and encourage his improvement. When he slips back into old patterns, gently confront the lying and remind him of how far he has progressed so far.
Make the choice to end the relationship, but not before you warn the person first. Explain that the lying is hurting your relationship and if it doesn’t stop, you’ll have to end it. Mention that you feel you can’t have a true connection with the person because of her refusal to be truthful and vulnerable. Explain that it isn’t fair to open yourself to a person who won’t return the gesture.