This isn’t news to many people, but living together before marriage is still linked to higher rates of conflict, divorce, and separation.
The researchers aren’t sure why, but they think that you’re more likely to choose to live with a bad mate that you normally wouldn’t choose to marry, but then once you’re living together it becomes easier to marry that person. The article says, “The Penn State team notes that research indicates that people choose riskier partners when cohabiting because they think cohabitation will be easier to break up than marriage. However, once a couple is living together, the fact that they share possessions, pets, and children and have invested time in their relationship may propel them to marry.”
Significantly, “living together in an unconventional relationship can make people less religious.” Notice the phrasing. It’s not that people who live together are less religious to begin with, but that they become less religious, or to put it more conventionally, their faith suffers. I think it also impairs the ability of a couple to completely give themselves to one another, or engage in total self-donation, as the Pope would put it.
(Thanks to Lane Core for the link.)