Tokyo (CNN) Japan's Princess Mako and her commoner fiance Kei Komuro have postponed their highly anticipated engagement and wedding until at least 2020, saying they were not yet ready for marriage.

The wedding, which had been set for November, was to be a momentous occasion for the country and the Japanese royal family, led by Emperor Akihito, who plans to abdicate in April 2019

But the couple said they were now having second thoughts about marrying so soon. "It is because of our immaturity and we just regret it," the couple said in a statement Tuesday.

Excitement swept the country when the Imperial Household announced last year that plans were underway for the princess to marry a commoner she'd met five years previously at International Christian University in Tokyo.

Before his introduction as the royal fiance, Komuro was better known as the "Prince of the Sea," after appearing in a beach tourism campaign for the city of Fujisawa, south of the capital.

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