Could it be that by being more picky, we give ourselves a better chance of staying together?
EDIT: I found a more recent one with a relative rate vs. marriages: http://www.telegraph.co.uk/news/uknews/12011714/Divorce-rate...
It may be that, as the article suggests, the decrease in % divorce rates has dropped partly due to the increase in social acceptability of cohabitation, allowing couples to try it out before getting married.
Nevertheless, taking simply divorce rates into account, the situation has improved from 20 years ago.