There are a couple of different statistics on the divorce rates. The best evidence I can find is a Family of the Americas study that found a divorce rate of .02%-3% There's an explanation of the statistical difference but I don't quite understand it. Either way, I'll take it. This page has some good explanation of why that might be true.
Here's what I think about it.
NFP works best when both people are on board, sharing the responsibility of keeping track of things and sharing the decision making about family planning. I make the observations and he keeps the chart. NFP requires communication, every day. It's a shared project, and it makes it hard to avoid things or hide things or hold onto resentments. It means that you are, naturally, talking all the time about what you want out of life, what you're worried about, what you think would be good for the family. All that communication has to help.
And that periodic abstinence (5-8 days/month on average) is really not that bad. Abstinence is a part of marriage. I don't know why we pretend like it isn't, like chastity is only a virtue until you get married, and then it's not a virtue anymore. Travel, sickness, depression, grief, childbirth, busy seasons... I'm sure you can think of examples. So NFP helps to build that self control little by little, so when those seasons of life hit, it's not such a surprise. We all find it shocking to hear stories about someone being unfaithful or leaving while their spouse is terribly sick or something, but it's hard to rely on virtues you've never exercised when everything else is falling apart. And the engagement/honeymoon cycle is pretty fun.
Sacrifice is a powerful way to show love. Marriage is all about sacrifice. This is just another way to lay down your life for your family.
Last night on the twitter party, the hashtag #MenLikeNFP was pretty funny. And then the #WomenLikeNFP played along too.
And there are lots of other (much better) bloggers celebrating NFP Awareness week, here, and here, and here!