When a couple says they never argue, it means they are each keeping a silent record of wrongs and grievances. They might successfully keep it bottled up until they die, but that's rare. Usually, they become teeming pots of resentment that bubble over in destructive ways.
Ongoing resentment acts out in random and confusing ways, in areas of life that have nothing to do with the original offense. This is why outbursts can seem like they come "out of nowhere."
In reality, the fuse has been burning for years. One of the healthiest things you can do for your marriage is to learn how to argue and disagree respectfully. This is a skill that takes practice.
And it takes courage. It's easier to keep your resentment bottled up and then take it out on your kids or your dog.
Whenever two people live in close proximity to one another, there will be disagreements. It's inevitable. And even more so when they are as different as a man and a woman are different. You didn't get married just because of your agreements and similarities. You also got married because of your differences and how those differences complemented one another.
Respectful arguments are healthy. Wives can disagree in a respectful way. Husbands can communicate their concerns in a loving way. No nagging and no browbeating.
Use objective statements, not accusatory statements. "When you do that, I feel disrespected," and not "You're so disrespectful!"
If you're angry, calm down before you speak.
Don't be passive-aggressive. Say what you mean.
Lots of divorced couples say their spouse never met their needs but never took the time to communicate their needs. What a tragedy.