However, half of the couples considered themselves married and described themselves as such to friends, family and acquaintances.
"None, zero." In your head The married and cohabiting couples were matched on the length of their relationship and relationship satisfaction, Coan said.
The key difference seems to be how people think of their relationship.
In the new study, Coan and his colleagues not only replicated the findings, they expanded them.
This time, they studied not only married couples, but also couples who were cohabiting.
There may be benefits to cohabiting, Coan said — at the very least, it's cheaper for two adults to live together versus separately, which has its upsides.