I think one message has to get out: When you divorce, you divorce not your spouse, but your family (and it doesn't matter who "gets" the kids). Ask the children of divorced parents, they'll tell you. Fortunately, this factor has convinced many of the generation now entering adulthood that they need to put more work into the relationship before marriage, to ensure that they will never do the same to their own children.
Actually I think it's created a generation intent to sleep together, not necessarily exclusivly for several years before contemplating marriage.