Who married Princess Marie Louise of Bulgaria?

Princess Marie Louise of Bulgaria (Bulgarian: Княгиня Мария Луиза Българска; born 13 January 1933) also known as Marie Louise Borisova Saxe-Coburg-Gotha, is the daughter of Tsar Boris III and Tsaritsa Ioanna and the older sister of Simeon II of Bulgaria. Her baptism in the Bulgarian Orthodox Church caused controversy at the time because her mother had promised to raise her children as Catholics. After the change in house laws into absolute primogeniture by her brother Simeon II, Princess Marie Louise became the head of the house of House of Saxe-Coburg and Gotha-Koháry.

Prince Karl of Leiningen (Karl Vladimir Ernst Heinrich; 2 January 1928 – 28 September 1990) was the second son of Karl, 6th Prince of Leiningen (1898–1946) and his wife, Grand Duchess Maria Kirillovna of Russia. She was the elder daughter of Grand Duke Kirill Vladimirovich of Russia and Princess Victoria Melita of Edinburgh. As such, Karl was a great-great-grandson of both Queen Victoria of the United Kingdom and Emperor Alexander II of Russia (as Victoria Melita and Kirill Vladimirovich were both grandchildren of Alexander II).