We keep meeting couples who say they never argue. We believe them, and we worry about them.
A friend once passed along a figure. Out of every eleven moments between two people, three or so ought to go badly. We have not read the study and we do not need to. A house with no bad moments has someone holding their breath in it.
So we fight. Not often, not politely, and all the way to the end.
Then comes the part that people who never fight never get to have.