Why Do Partners Lie?

People lie to preserve something they value -- their self-esteem, their peace of mind, their meal ticket. So the real question is not "Why did he lie?" but "What is he protecting?"
Instead of becoming a human lie-detector test, it's often more productive to look at the overall pattern of trust/index.html">keeping secrets. Does this person deceive family members, friends, employers? You may have a compulsive liar on your hands, someone who uses lying as a survival tool and needs significant work and help before she is ready to be truly honest in a relationship.