Louis I, Grand Duke of Hesse
In 1776, he became engaged to Sophie Dorothea of Württemberg, eldest daughter of Frederick II Eugene, Duke of Württemberg. The engagement was broken off so that Sophia Dorothea could marry Louis's recently widowed brother-in-law Tsarevich Paul Petrovich, son and heir of Catherine II "the Great", Empress of Russia. He received a monetary compensation when the engagement was broken.
Paul-Philippe Hohenzollern
In 1918, the crown prince of Romania (the future King Carol II) married Zizi Lambrino. The wedding was annulled the following year because it contravened the royal house's statute—Lambrino was both a Romanian and a commoner, and the marriage took place without the consent of the king. The couple had one son, Carol Lambrino, the father of Paul Hohenzollern. In 1921, Crown Prince Carol married Princess Helen of Greece and Denmark, and they had a son who became King Michael I of Romania.