What is interesting is that the Lutheran’s (and that includes the ELCA) and the RCC have similar and lower divorce rates. I suspect that part of it is that often both have rather in depth pre marital meetings with the priest/pastor.
That and in the more “conservative” parts of both confessions (for lack of a better term), we are really not an “American” church. We still do things differently than the mega church down the road.
The pre marriage counseling and understanding of the meaning of evangelizing each other I think helps the longevity of marriage. Other practices like NFP increase communication in the relationship, which furthers closeness.