Yes, Japanese people do get divorced. It's just that American families get divorced more. This confuses Shigeru Miyamoto. He didn't make Wii Fit for single parents! According to CNET's Crave blog:
While Wii Fit has become somewhat of a family sensation in Japan, Miyamoto says he's not sure how an American audience will receive the game. When we asked Miyamoto what he expected from American consumers, he noted that on average, American families are apart more often than those in Japan. A lot of families have parents who have separated or divorced, so it's tougher to predict the role family will play in the American response to Wii Fit—and we couldn't agree more.