Question: What cousin did the monarch considered a mere constitutional figurehead his whole life marry ?

text: List of coupled cousins
Royalty in Europe
The royal couples listed below are but a sampling of the innumerable marriages that have occurred between cousins , of varying degrees , from royal or noble houses . Such royal intermarriages have been common , as it has generally been deemed inappropriate for royals to marry commoners .
This is a list of prominent individuals who have been romantically or maritally coupled with a cousin.
Person Spouse Married Year Relationship Common ancestor ( s )
Prince Adalbert of Bavaria Infanta Amalia of Spain 25 August 1856 1856 Fifth cousins Philip William , Elector Palatine and Landgravine Elisabeth Amalie of Hesse-Darmstadt
Prince Adalbert of Bavaria Countess Augusta of Seefried and Buttenheim ( daughter of Princess Elisabeth Marie of Bavaria ) 12 June 1919 1919 Second cousins once removed Ludwig I of Bavaria and Therese of Saxe-Hildburghausen
Prince Adalbert of Prussia Princess Adelaide of Saxe-Meiningen 3 August 1914 1914 Second cousins Ernst I , Prince of Hohenlohe-Langenburg and Princess Feodora of Leiningen
Adolf , Duke of Holstein-Gottorp Christine of Hesse 17 December 1564 1564 Second cousins once removed Eric II , Duke of Pomerania and Sophie of Pomerania , Duchess of Pomerania
Adolf I , Prince of Schaumburg-Lippe Princess Hermine of Waldeck and Pyrmont 25 October 1844 1844 First cousins George I , Prince of Waldeck and Pyrmont and Princess Augusta of Schwarzburg-Sondershausen
Adolf Frederick , King of Sweden Louisa Ulrika of Prussia 29 August 1744 1744 Third cousins George , Duke of Brunswick-Lüneburg and Anne Eleonore of Hesse-Darmstadt
Adolf Frederick I , Duke of Mecklenburg Anna Maria of Ostfriesland ( first wife ) 4 September 1622 1622 First cousins Adolf , Duke of Holstein-Gottorp and Christine of Hesse
Adolf Frederick I , Duke of Mecklenburg Duchess Marie Katharina of Brunswick-Dannenberg ( second wife ) 1635 1635 Third cousins once removed Magnus II , Duke of Mecklenburg and Sophie of Pomerania , Duchess of Mecklenburg
Duke Adolf Friedrich of Mecklenburg Princess Viktoria Feodora of Reuss-Schleiz ( daughter of Heinrich XXVII , Prince Reuss Younger Line ) 24 April 1917 1917 Fourth cousins Frederick II Eugene , Duke of Württemberg and Princess Friederike of Brandenburg-Schwedt
Adolph , Landgrave of Hesse-Philippsthal-Barchfeld Princess Louise of Saxe-Meiningen 18 October 1781 1781 First cousins once removed Philip , Landgrave of Hesse-Philippsthal and Catherine von Solms-Laubach
Prince Adolph of Schwarzburg-Rudolstadt ( father of Princess Marie of Schwarzburg-Rudolstadt ) Princess Mathilde of Schonburg-Waldenburg 27 September 1847 1847 Double first cousins once removed Frederick Charles , Prince of Schwarzburg-Rudolstadt and Princess Friederike of Schwarzburg-Rudolstadt ; Frederick V , Landgrave of Hesse-Homburg and Princess Caroline of Hesse-Darmstadt
Adolphe , Grand Duke of Luxembourg Grand Duchess Elizabeth Mikhailovna of Russia ( first wife ) 31 January 1844 1844 Second cousins once removed Charles II , Grand Duke of Mecklenburg-Strelitz and Princess Friederike of Hesse-Darmstadt
Adolphe , Grand Duke of Luxembourg Princess Adelheid-Marie of Anhalt-Dessau ( second wife ) 23 April 1851 1851 Fourth cousins Louis VIII , Landgrave of Hesse-Darmstadt and Countess Charlotte of Hanau-Lichtenberg
Prince Adolphus , Duke of Cambridge Princess Augusta of Hesse-Kassel 1 June 1818 1818 Second cousins George II of Great Britain and Caroline of Ansbach
Adolphus Frederick II , Duke of Mecklenburg-Strelitz Princess Maria of Mecklenburg-Güstrow ( daughter of Gustav Adolph , Duke of Mecklenburg-Güstrow ) 1684 1684 First cousins once removed Johann VII , Duke of Mecklenburg and Sophia of Holstein-Gottorp
Adolphus Frederick III , Duke of Mecklenburg-Strelitz Princess Dorothea of Schleswig-Holstein-Sonderburg-Plön ( daughter of John Adolphus , Duke of Schleswig-Holstein-Sonderburg-Plön ) 16 April 1709 1709 Third cousins Adolf , Duke of Holstein-Gottorp and Christine of Hesse
Adolphus Frederick V , Grand Duke of Mecklenburg-Strelitz Princess Elisabeth of Anhalt April 17 , 1877 1877 Second cousins once removed Charles II , Grand Duke of Mecklenburg-Strelitz and Princess Friederike of Hesse-Darmstadt
Afonso , Prince of Portugal Isabella of Aragon , Queen of Portugal 1490 1490 Second cousins John , Constable of Portugal and Isabel of Barcelos
Afonso II of Portugal Urraca of Castile , Queen of Portugal 1206 1206 Second cousins once removed Ramon Berenguer III , Count of Barcelona and Douce I , Countess of Provence
Afonso III of Portugal Matilda II , Countess of Boulogne ( first wife ) 1239 1239 Third cousins once removed Fulk , King of Jerusalem