I’ve seen this kind of stat before, but I happened to stumble on this page - an article informing us that in the United States a couple that does not live together prior to getting married has a 20 percent chance of being divorced within five years, whereas if the couple has lived together beforehand, that number jumps to 49 percent. In other words, a couple is nigh-on two and a half times more likely to divorce if they live together beforehand.
Clearly all the indication is that the try before you buy method doesn’t guard against the marriage ending - quite the opposite it would appear. If you’re still in your nascent stages of economics, you might be tempted to ask the question: what is it about living together prior to marriage that increases your chances of being a divorcee? But a better way of doing economic analysis is to first realise that it may not be the living together premaritally that increases the probability of divorce, it may well be, and in fact almost certainly is, more distal factors associated with what kind of people live together before marriage and which do not.
For example, many Christians who would not live together before marriage for faith-based reasons are likely to be the kind of people that take marriage seriously enough not to divorce. By equal measure, many couples who will easily disregard any (admittedly declining) social norms about pre-marital co-habitation will probably just as equally disregard any (admittedly declining) social norms about the stigma of divorce too. A corollary of this is that if you are the sort of person who easily disregards social norms, you are perhaps more likely to be the sort of person who more easily disregards niceties and mindful considerations that keep a marriage safe from divorce.