The richer people are today, the more likely they are to get married - and stay married

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The US divorce rate has fallen in the last decade.

• The divorce rate in the US declined 18% between 2008 and 2016, according to a new analysis.
• That's likely because couples today are waiting until they're older and more established, professionally and financially, to marry.
• Money and education tend to protect against divorce.

Bloomberg Businessweek recently published an article on the declining divorce rate in the US.

According to an analysis by University of Maryland sociology professor Philip Cohen, the divorce rate decreased 18% between 2008 and 2016. And it's poised to drop even further.

This isn't because the US population is getting older - or older couples are less likely to get divorced, either. When Cohen controlled for age, the divorce rate declined 8%.

On the surface, these findings might seem like cause for celebration: Relationships are stabler! Yet the reality, experts say, is more nuanced.

Marriage has, over the past few decades, become the province of the elite. Relatively wealthy and educated Americans are more likely to marry than their less well-off counterparts - and marriages between wealthy, educated people tend to be stronger.

People are also waiting longer to tie the knot than they did in the past, often living together before putting a ring on it. That's also a likely factor in the declining divorce rate: People have a chance to run a "trial marriage," as INSIDER's Kim Renfro reported, and see if it's worth making it official.

This is all to say: The couples choosing to get married today are the couples who are less likely to divorce in the first place.

Couples are only getting married after they've established themselves professionally and financially

"Marriage is more and more an achievement of status, rather than something that people do regardless of how they're doing," Cohen told Businessweek. Only once you've, say, completed your education and landed a well-paying job will you think about marriage.

As of 2017, the most common age to get married was 27 for women and 29 for men, according to US Census Bureau data. And research led by Nicholas Wolfinger, a professor at the University of Utah, suggests that couples who marry in their late 20s are least likely to divorce (compared to people who marry younger or older).

Meanwhile, a post on the Bureau of Labor Statistics website highlights results from the National Longitudinal Survey of Youth (1979), which looked at the marriage and divorce patterns of a group of young baby boomers. According to that research, over half of couples who didn't complete high school ended in divorce, compared with about 30% of marriages between college graduates.

It may come down to the fact that lower educational attainment predicts lower income - which in turn predicts a more stressful life. As Eli Finkel, a psychologist at Northwestern University and a professor at the Kellogg School of Management, previously told Business Insider, "It's really difficult to have a productive, happy marriage when your life circumstances are so stressful and when your day-to-day life involves, say three or four bus routes in order to get to your job."

To be sure, waiting to propose until you're almost 30 and have hit some career milestones doesn't divorce-proof your marriage - though if you ask a relationship expert, they'll tell you not to equate divorce with the failure of the relationship.