"I know you were flirting with someone else!"
The Fight: When people think of jealousy issues in relationships, they often think of flirting or, worse, affairs. But jealous feelings can come up in a host of nonromantic, nonsexual scenarios. If one partner is saddled with responsibilities of a stay-at-home parent while the other goes to work (or from the other perspective, one gets to be at home with family while the other has to go to work), that can cause friction, as can one couple's success, earnings, outside hobbies, or even their fitness level.
The Fix: "If you're jealous, your point of view is that you're insecure, and you don't think you have value," Heer says. "You need to find your value, and what you value, in life outside of your relationship in order to make things different. Know what makes you valuable compared to others."