The Times reports that:

Couples who live together before they get married are less likely to stay married, a new study has found….The likelihood that a marriage would last for a decade or more decreased by six percentage points if the couple had cohabited first..

Obvious conclusion: Don’t live together before you get married, if you want to stay married.

But this is another one of those “correlation does not imply causation” posts.  Here are two interpretations that do not imply the obvious conclusion.

First, suppose one partner is reluctant to get married and has doubts about the relationship. More information would be helpful to decide whether to stay together or break up. If the couple cohabit, that will give them valuable information.  On the other hand, couples who are more confident about their relationship are more likely to get married straight away.  Hence, more stable couples are less likely to live together before marriage than less stable couples.  Living together per se is not the problem.  The real problem is that a deeper source of instability is correlated with cohabitation.

Second – and this theory is implicit in the research – more religious couples are less likely to get divorced and less likely to live together before marriage.  Again, selection explains the data and not cohabiting per se.

The empirical results are interesting but you can carry on living in sin without worrying that this is going to lead to the collapse of your marriage.  That may happen but it’s because you really hate each other and religion is not providing the glue to keep you together.