They may cohabit before marriage or spend more time dating their eventual spouse.
Some may simply be more selective.
Therefore, the lower divorce rate associated with later marriage may partly reflect who chooses to marry later rather than simply what age does to a person.
This is why responsible researchers describe an association rather than claiming that postponing a wedding will automatically prevent divorce.
Waiting Forever Is Not Necessarily the Answer Either
The statistics should also not be interpreted as evidence that every additional year of waiting continuously improves marital prospects.
Marriage researchers have debated whether the protective effect of postponing marriage eventually levels off.
The strongest and most consistent finding is that marrying extremely young carries elevated risk.
Beyond the twenties, the relationship becomes more complicated.
Different datasets, generations and statistical models can produce somewhat different estimates. Marriage at 30 should therefore not be treated as possessing a magical advantage over marriage at 29, nor should a person assume that postponing marriage until 40 will automatically create a more stable relationship.
There is no universally perfect age to marry.
The important lesson is broader.
Marriage is usually a more consequential decision than young people initially realize, and allowing enough time to develop emotionally, financially and personally can improve the conditions under which that decision is made.
Marriage in America Is Happening Later Anyway
American marriage patterns have changed dramatically across generations.
The NLSY79 participants belonged to a generation in which marriage often occurred substantially earlier than it does for many Americans today.
The BLS analysis notes that women in the cohort married younger than men and that much of the cohort had entered marriage by their late twenties.
Modern adults are increasingly spending more of their twenties completing education, establishing careers or living independently before marriage.
That cultural shift means later marriage is not necessarily viewed as unusual in the way it once was.
For many people, the years before marriage are now a significant stage of adult development rather than simply a waiting period.
Those years can be used to build careers, friendships, independence and self-knowledge.
They can also provide opportunities to understand relationships without immediately attaching the legal and financial consequences of marriage.
Statistics Cannot Tell You Whether Your Marriage Will Succeed
Perhaps the most important caution is that divorce statistics should never be treated like individual destiny.
A couple marrying at 21 is not automatically headed for divorce.
A couple marrying at 37 is not automatically protected from it.
Relationships are shaped by countless factors that cannot be summarized by a person's age on their wedding day.
Communication matters.
Trust matters.
Financial behavior matters.
Compatibility matters.
Shared values matter.