Does living together before marriage affect divorce risk?

The research has shifted substantially, and the answer people usually cite is out of date.

What older studies found. Research from the 1970s through the 1990s consistently reported that couples who cohabited before marriage had higher subsequent divorce rates. This became a widely repeated finding, sometimes called the cohabitation effect.

Why the finding changed. Two explanations have largely displaced the original interpretation:

Selection. When cohabitation was uncommon and socially disapproved of, the people who did it were unusual — less religious, less traditional, more accepting of divorce as an option. The association was substantially about who cohabited, not about cohabitation causing anything. As the practice became normal, that selection effect diminished, and so did the measured association.

Timing and intent, not cohabitation itself. Later work found that what matters is the age and commitment level at which a couple moves in together, rather than whether they do. Couples who move in with a clear mutual commitment — engaged or with an explicit shared plan — show no elevated risk. Those who slide into living together for convenience, cost or inertia show worse outcomes, apparently because shared leases, pets, furniture and finances create constraints that make it harder to leave a relationship that is not working. This is called the inertia hypothesis or sliding versus deciding.

Moving in young is independently associated with worse outcomes, and much of the original effect appears to be an age effect.

Where the evidence stands now: most recent research finds little or no increased divorce risk for cohabitation with commitment, and studies controlling for age at coresidence find the effect largely disappears.

The practical reading is not about the arrangement but the decision — whether moving in was chosen deliberately or arrived at by default.