John Gray, author of Men Are From Mars, Women Are From Venus, discusses infidelity. If you found out your best friend was cheating on her husband, would you feel obligated to tell him? What if it was the other way around?br br See more from Dr. John Graybr And br YourTango is your source for smart talk about love, sex, dating and relationships. Whether you're married, single, taken, engaged or "it's complicated," check out our videos for the best love and relationship news, entertainment and advice.