Princess Ayako of Japan just married Kei Moriya, a 32-year-old employee of a shipping company. She gave up her royal status "for love," as many news sites put it, because her new husband is a commoner. At first glance, it seems like a sweet tale about the triumph of romance over tradition. But look a bit deeper, and you'll see a story about a royal family that may be destroyed by its own dumb rules. And a good lesson for today's little girls--in thrall to Disney princesses and Meghan Markle--about what being a princess truly means.

At issue is the law governing the royal family, the Imperial Household Law of 1947, passed during the U.S. occupation of Japan and intended to reduce the size (and expense) of the Japanese imperial family. The new law eliminated some side branches of the imperial family and outlawed the succession of illegitimate sons (born of concubines, for example) to the throne. It also required female royals who married commoners to leave the royal family, supposedly for fear of "diluting" the royal line with the resulting children. But no such rule exists for male royal family members. They can marry and have children with commoners and still ascend to the imperial throne with no fear of dilution.

In fact, 58-year-old Crown Prince Naruhito, heir to the throne, married a commoner. If they had a son, he would be next in the line of succession. But they had only daughters and women cannot inherit the throne under that 1947 law. There are only four people who can: Crown Prince Naruhito, his 52-year-old brother Prince Akishino, Akishino's 12-year-old son, Prince Hisahito, and the emperor's 82-year-old brother Prince Hitachi, who has no children. Thus, the fate of this ancient lineage, dating back more than 2,000 years, rests entirely on the possible future offspring of a single 12-year-old boy.

With Ayako's departure, the entire royal family is now down to only 18 members. It keeps dwindling as the princesses marry--nine have left the royal family through marriage to commoners since 1947 and a tenth is engaged to a commoner and will likely leave within two years. Given these stats, you might think that Japanese lawmakers would consider changing the law. In fact, they had the perfect opportunity recently, when 84-year-old Emperor Akihito announced his desire to step down, due to his advancing age and declining health. Emperors are supposed to rule for life--there's no legal provision for them to quit or retire--so the Japanese Diet had to pass a special law allowing Akihito to abdicate, which he plans to do in March. At the time, some lawmakers proposed adding a resolution to the law allowing women who marry commoners to remain in the royal family, but conservatives opposed the change and it did not become part of the final law.

Girls finally get an equal shot at the British throne.

Elsewhere in the world, monarchies are doing away with primogeniture--the law that favors sons over daughters in succession to the throne. For example, Queen Elizabeth II, Queen Elizabeth I, and Queen Victoria--three of Britain's longest-reigning and most beloved monarchs--only became queens because they had no brothers. But in 2015, the U.K. abolished primogeniture just before the birth of Queen Elizabeth's first great-grandson Prince George. Without that change, George would have been next in the line of succession after his grandfather Prince Charles and father Prince William--leapfrogging over his older sister, Princess Charlotte. Under the new law, Charlotte keeps her place in line.

As for the former Princess Ayako, she told the press that she was raised to consider it her duty to support the royal family in its work, and would continue to do so as much as she is able. She seems well prepared for a non-royal life. She began her education at Japan's prestigious Gakushuin school, which was created for the Japanese nobility. But instead of continuing through Gakushuin's university program, she attended Josai International University's Faculty of Social Work Studies, spent two years studying in Canada, and now works as a research fellow at Josai.

This background may stand her in good stead in the coming years, as she will likely need a job. When Ayako gave up her royal status she also gave up her royal allowance. The government gave her aplaceholder lump sum worth about $950,000, but that's all she'll ever get.