Overall, I'd say the greater risk factors for unhappiness in marriage were not IQ but were factors outside the marriage relationship that the couple couldn't help (health issues, challenges with children, or other adults zooming in and trying their best to break up the marriage)... and sometimes combined with having grown up in a household where their parents marriage didn't last.
There's definitely something to that. Research shows that it's usually external stressors that lead to the breakdown of families... typically involving money, health, and children.
And where I'd suggest that gifted couples have the advantage is that they're better able to manage those stressors. They're better at making and managing money. They're better at analyzing health issues and advocating with doctors for more positive outcomes. And they're better at coming together as a team and managing issues with the children.
Where gifted couples are at a disadvantage: emotional intensities.
