Men Are From Mars, Women Are From Venus by John Gray

In his classic guide to understanding the opposite sex, Dr. John Gray, provides a practical and proven way for men and women to improve their communication and relationships by acknowledging the differences between them.

Once upon a time Martians and Venusians met, fell in love, and had a happy relationships together because they respected and accepted their differences. Then they came to Earth and amnesia set in: they forgot they were from different planets.