Married life is sometimes inconvenient and even demanding. Cohabitation for convenience is poor preparation for that kind of commitment. Research bears this out. One study, conducted by researchers at the University of Chicago and the University of Michigan, concluded that couples who cohabit tend to experience superficial communication and uncommitted decision-making once they are married. Sure, you might save the price of monthly rent, but you're sacrificing something more valuable.
Engagement is more than just time to plan the party.
It is a time for deeper discussion and more thorough reflection, which are best carried out in a detached way. Couples who are living together do not have the luxury of such detachment. So whatever expenses you save, you'll likely pay more in the end. Studies consistently show that couples who live together score significantly lower in both marital communications and overall satisfaction. On the surface, a trial run at marriage may seem to make sense, allowing one to screen out less compatible mates.