Before I tell you about that one thing, let me establish an important fact. Anytime you enter a conflict with the goal of determining who is right and who is wrong, you've probably already failed. Why? Because research shows that arguments between couples rarely reflect an issue where only one of the partners has the right opinion. In most cases, there is either no “right” answer (the disagreement is over opinion or perspective) or the solution is actually found in parts of what they both are saying.
But reason often flies out of the room when I feel challenged by my wife. In that moment, my natural assumption is often “I'm right; you're wrong. If you'd just shut up and listen to me you'd probably learn a thing or two.” When Sharon has the same idea, the battle begins.
A common communication technique is to focus on listening, but I've always found that a hard thing to do when feelings are being whipped into a frenzy. But there is different action I've found easier to take, even in an emotional moment: BE CURIOUS. What I love about moving to curiosity is that it does not require me to change my opinion about the argument at all. All it asks me to do is wonder why my partner feels so strongly about this issue.
As soon as I can grab on to curiosity, my mouth usually closes, I start listening, and I probably ask questions. You know what? Every time either one of us does this, the other starts doing the same. Before you know it, we are both explaining what we believe, or how we think, or the way we feel… but it’s not an argument anymore. Each of us is inviting the other into the conversation.
Try this: the next time you get into an argument, imagine a big red exclamation mark bouncing above the other person’s head. That represents your intent in the moment: to emphatically state your position. When you see the red mark, change it in your mind; turn it into a blue question mark. Let that represent all the stuff you don't know about why he/she thinks and feels the way they do. Stop the debate; stop trying to figure out right or wrong until you fully understand their point of view.
Let your relationship win the argument by moving into curiosity instead of conflict.