Do not investigate the lie. You will not accomplish anything positive by trying to catch him in a lie. Even if you find hard evidence of deception, your boyfriend may only tell another lie to conceal the first one. Also, once you start becoming a lie detector, it will never end. This is not the role you want to play in your relationship. It is destructive and may even be unethical.

Assume the best. If your boyfriend is lying to you, you will find out in time. But you will look insecure if you make accusations, so speak to what you really know.

Be confident. Your attitude may not turn him into a truth monger, but you'll feel better about yourself. If you feel good about yourself, you will seek positive things in life, which may mean there is no longer a place for a lying boyfriend.

Don't try to fix him. If you have children, it is your job to teach them the difference between a truth and a lie. But you do not have this obligation to your boyfriend. The only person you can change is yourself. Be honest and forthright in the way you handle him.

State your expectations. Tell your boyfriend you are honest with him and that you expect honesty in return. You don't need to argue with him or outline the lies he has told you. Put him on notice that if he can't be honest with you, then the relationship will no longer meet your needs.

Make good on your word. Move on if you do not see a change in his behavior.