Frederick Louis, Hereditary Grand Duke of Mecklenburg-Schwerin

Frederick Louis married three times, and all three of his marriages proved happy. At Gatchina near Saint Petersburg) on 12 October 1799 (Old Style - 23 October), he married Grand Duchess Elena Pavlovna of Russia, daughter of Tsar Paul I of Russia, who incidentally died only five months later. Among Elena's siblings were Tsar Alexander I, the future Tsar Nicholas I, and a future queen of the Netherlands. The couple had two children:

Paul Frederick of Mecklenburg-Schwerin (1800-1842) Grand Duke of Mecklenburg-Schwerin, who in 1822 married Princess Alexandrine of Prussia (1803-1892), daughter of Frederick William III of Prussia
Marie of Mecklenburg-Schwerin (1803-1862), who in 1825 married Georg, Duke of Saxe-Altenburg, first cousin of her sister-in-law Alexandrine.

Elena died in 1803. Seven years later, in 1810, Frederick married Princess Caroline Louise of Saxe-Weimar-Eisenach, daughter of Charles Augustus, Grand Duke of Saxe-Weimar-Eisenach. They had three children:

Albert of Mecklenburg-Schwerin (1812-1834)
Hélène of Mecklenburg-Schwerin (1814-1858), who in 1837 married Prince Ferdinand Philippe, Duke of Orléans (1810-1842) eldest son of Louis Philippe I, King of the French
Magnus of Mecklenburg-Schwerin (1815-1816)

Caroline died in 1816 aged 29. On her deathbed, anxious for the future of her children, she enjoined her husband to marry her first cousin (her mother's sister's daughter) Princess Auguste, daughter of Frederick V, Landgrave of Hesse-Homburg. Not long after Caroline's death, Frederick's court made known the late Landgravine's expressed wishes to her near relatives, who acted upon the matter. Princess Auguste was forty years old, the same age as Frederick, and the prospect of mothering Caroline's infant children, as also of mentoring his teenage children by Elena, was deeply attractive to her. At the instance of her parents, she readily agreed to the proposal.

On 03 April 1818, Frederick was united in marriage to 41-year-old Princess Auguste. Incidentally, four days later, on 07 April 1818, Auguste's brother Frederick married Princess Elizabeth of the UK, daughter of George III. Both of these marriages, featuring middle-aged couples, proved childless but extremely happy.

Frederick and Auguste did not have children but were happy together during the nineteen months that providence granted them with each other. Frederick died in November 1819. It soon became evident that Caroline had judged her cousin well and had made an inspired choice. Auguste never remarried, remained in Mecklenburg-Schwerin for the rest of her life, and devoted herself to the care of her step-children. She had close and loving bonds with all four of them, but particularly with the youngest, Helene, who she raised from the age of four. Unfortunately, Landgravine Auguste was destined to outlive all four of her beloved step-children. She died in 1871 aged 94.

Frederich was buried at the Helena Paulovna Mausoleum. All three of his wives lie buried beside him.