The US divorce rate isn't as high as it appears. The 50% figure includes everyone who gets married in a certain year but also includes many people who are getting married for the second, third, or fourth time. That means that 50% of people who marry for the first time are NOT getting divorced. Also 50% or all people who have ever married for the first time are NOT divorced. The ability of people to stay married is actually much better than 50% because the figure is being loaded by people who are constantly jumping from marriage to marriage. If we really want to know what the divorce rate is then find a study that focuses on first time marriages only.
Apparently the divorce rate in Japan isn't high enough as they have these crazy agencies:
Japanese murder exposes world of hired marriage wreckers - Times Online