The divorce rate is a little cooked. Those who suck at marriage are represented over and over. Those who are great only get included once each.
I always shudder when I hear a couple claim that they negotiate everything.
Negotiating is how we establish an exchange rate. If you have chickens to trade and I have oranges, negotiating the rate requires I talk down the quality of your chickens, and talk up the freshness and sweetness of my oranges; while you do the opposite.
That hardly sounds like a solid basis for a satisfying relationship.
The only workaround I've found is if I just give you 100% of my oranges, and you give me 100% of your chickens; then I can be openly appreciative of their lovely plumage and delicious eggs without hurting my supply.
That'll cost you all of your chickens though. Hope you like oranges.
But it is also that those who stay together, aren't necessarily doing well. Time served doesn't equate to a good relationship.
Or, you can give the best of your oranges and I can give my best chickens.