The hidden key to a healthy relationship is not just managing money but understanding how the other approaches money. Every couple argues about money. It doesn't matter if you've been married for 40 years or dating for 4 months, money touches every decision you make as a couple - from the $5 cup of coffee to the $50,000 car. And when the two of you don't see eye-to-eye on how much to spend or how much to save, that's when arguments turn into ugly toxic fights that leave both persons feeling hurt and angry. It's why money has become the number-one cause of divorce in the U.S. Obviously, something needs to change.