Earlier quoted context omitted.
The root cause of fight is that partners disagree over something that is important to both (likely related to some core value). The contributing factor is oftentimes stress, people are not able to be perfect under stress and sleep deprivation. Self-control and compassion don't make disagreement or bad feelings over important things disappear. They are still present. The "never fight" relationships (not just marriage,…
> The "never fight" relationships (not just marriage, but also friendships) are either "we do things as separately as possible" or one of the two ceased to talk about his or her issues. You missed one more option: "we can discuss a problem without involving emotions or clinging to our opinions too much".
How exactly do you have no emotions in a marriage disagreement? Most arguments are about emotions. No one argues about things they aren’t emotional about (unless it’s a proxy argument for something they are emotional about).