Louis CK has a good bit about this too:

"Divorce is always good news. I know that sounds weird, but it's true because no good marriage has ever ended in divorce. That would be sad. If two people were married and ... they just had a great thing and then they got divorced, that would be really sad. But that has happened zero times."

He is wrong about this one.

The quality of marriage is neither binary nor one-dimensional, it varies over time, and most importantly, can be influenced for the better or worse.

Its graph over time is also also not monotonic decreasing.

I fear that some marriages get divorced at a local minimum.

In college I had a sociology class where the professor had studied happiness in marriage. He ran a survey asking how happy people were with their marriage. 5 years later, he ran a follow up survey to people who said in the first survey that they were unhappy in their marriage and the only reason they would not get divorced was because of (children, religious doctrines, etc).

He was shocked to find, that of these marriages that were the least happy, something like 20% went ahead and got a divorce anyways, but, of the other 80%, their happiness scores were no different from the general population.

Moral of the story, perhaps people are a little too quick to pull the plug on a marriage.

With a few exceptions, divorced marriages are all moderately unsuccessful marriages. The truly horrible marriages are the ones that last, but shouldn't.

Exceptions: Parent suicide, Parent murder + prison, Divorced parent suicide, Divorced parent assault + prison, Divorced parent murder + prison.

And particularly horrible ones:

Parent murder + no prison, Divorced parent murder + no prison.

The so-called "silent divorce."

While not all unhappy marriages end in divorce, it's at least safe to say that almost all marriages ending in divorce were not happy.

True dat.