So what does that mean for regular folks? The ones whose marital ups and downs don't play out on the world stage, but nonetheless come into sharper focus when couples melt down so publicly?
Up to 60 percent of divorces in the United States, in fact, stem from "low-conflict" marriages, Haag writes in her book, citing a study by marriage researcher Paul Amato. Marriages that aren't marred by abuse, addiction, repeated infidelity or other "high-conflict" issues, in other words, actually account for the majority of divorces.
So where do such marriages go wrong?
Fade to oblivion
There's rarely a singular tipping point, says Edward M. Hallowell, director of the Massachusetts-based Hallowell Centers for Cognitive and Emotional Health and co-author of "Married to Distraction: How to Restore Intimacy and Strengthen Your Partnership in an Age of Interruption" (Ballantine Books).
More often it's a slow erosion toward cohabitating strangerdom.
Basically, we stop paying attention to each other.
"The ambient noise of life takes over," Hallowell says. "There's no big conflict; couples have just lost touch with each other, lost the fun, lost the moments of sustained attention because we live surrounded by this buzz."
Sometimes the buzz is quite literal.
"One woman asked me, 'Is it normal that my husband lays his BlackBerry next to us when we're having sex?'" Hallowell says. "I said, 'I don't know which is odder. That he's doing it or that you have to ask.'"
But technology is only part of the problem.
"People don't realize they're drifting apart because they're so overly bombarded with messages and stimuli and they're crazy, busy, running, keeping up with everything," he says. "In the absence of a major blowup, you just wake up one morning feeling, 'I'm not passionate about this person. At all.'"
Of course, some forces working against a marriage are more overt.
"There are common traps that couples fall into," says Fran Cohen Praver, clinical psychologist and author of "The New Science of Love: How Understanding Your Brain's Wiring Can Help Rekindle Your Relationship" (Sourcebooks). "Unequal power. The blame game — a disastrous war that no one wins. Self-fulfilling prophesies where this negative fortunetelling goes on between people. There's something about yourself that you don't like so you disconnect it from your conscious, split it off and project it onto the other person."
Just to name a few.
Rekindling the passion
The good news, experts agree, is that "low-conflict" problems are extremely solvable. No addictions to overcome, no affairs to forgive, no crushing debt from which to emerge.