Many dating couples opt to live together before deciding to marry, because they believe that it is a responsible and prudent thing to do.

They reason that cohabitating together will be like a trial marriage. They will learn all about each other’s habits and discover whether they are truly compatible. And when they do finally marry, that they’ll have a head start because they’ll be knowledgeable of each other, and they will have already negotiated many of their differences. They have the best of motivations, but unfortunately it’s not actually how it works.

https://smartloving.org/cohabitation-myth/