[amihow]

It is only those people who are disinclined to divorce in the first place who love enough to practice NFP.

[Brian Kopp DPM]

We taught NFP for ten years. We saw it improve marriages among couples that previously contracepted in ways that would indeed prevent divorce.

Its a chicken-and-egg argument. In some cases, couples practice NFP because of a deep preexisting commitment to Christian principles.

In some cases, couples practice NFP because of baser motives (couples where the wife almost died from blood clots from the Pill, for instance.)

The deeply committed couples are drawn to NFP, but NFP itself does indeed build relationships and helps them grow deeper.

And last but not least, it is a sacrifice to practice NFP, and God provides Grace to those couples willing to make that sacrifice out of love for Him and His Natural Law.

That Grace builds and saves marriages.