Ernest Louis, Grand Duke of Hesse

On 19 April 1894, at Schloss Ehrenburg, Ernest Louis married his maternal first cousin, Princess Victoria Melita of Saxe-Coburg and Gotha ("Ducky"), the daughter of his mother's brother, Prince Alfred. The match was actively encouraged by their mutual grandmother, Queen Victoria, who attended the wedding. At the wedding, Ernest's youngest surviving sister, Alix, met and became engaged to marry Tsarevich Nicholas of Russia, and the excitement of that imminent match threw the nuptial celebrations into the shade.

Ernest was still devastated by the memory of his daughter's death thirty years later. "My little Elisabeth," he wrote in his memoirs, "was the sunshine of my life."[2]

Ernest and Victoria Melita had two children:

• a daughter, Elisabeth, born on 11 March 1895, who died of typhoid fever on 16 November 1903 at age eight,
• a son, stillborn on 25 May 1900.

Ernest and Victoria entertained in style, frequently holding house parties for young friends (anybody above 30 was deemed "too old" by Victoria), dispensing with formality on those occasions to indulge in fun and frolic; Victoria's cousin Prince Nicholas of Greece and Denmark remembered one stay with them as having been "the jolliest, merriest house party to which I have ever been in my life."[3] These revelries were more in keeping with Victoria's inclinations than Ernest's. Their marriage was unhappy due to differences in temperament and attitude. Fond as she was of revelry, Victoria was less enthusiastic about fulfilling her public role. She avoided answering letters, put off visits to elderly relations whose company she did not enjoy, and talked to people who amused her at official functions while ignoring people of higher social or official standing whom she found boring.[4] Victoria's inattention to her duties provoked quarrels with Ernest. The young couple had loud arguments which sometimes turned physical. The volatile Victoria shouted, threw tea trays, smashed china against the wall, and tossed anything that was handy at Ernest during their arguments.[4]

Queen Victoria was saddened when she heard of the trouble in the marriage from Sir George Buchanan, her chargé d'affaires at Darmstadt, but because of their daughter, Elisabeth, she refused to consider permitting her grandchildren to divorce. Ernest also held off from divorce mainly for this reason. He adored his daughter to distraction and lavished his time and attention on her. The child reciprocated her father's affection, preferred the company of her father to that of her mother.[5] Meanwhile, all efforts to rekindle the marriage failed; Victoria took to spending most of the year in the south of France, spending vast sums in expenses and at the card-tables in Monte Carlo. When Queen Victoria died in January 1901, significant opposition to the end of the marriage was removed.[6] The couple were divorced 21 December 1901 on grounds of "invincible mutual antipathy" by a special verdict of the Supreme Court of Hesse. After the divorce had come through, Victoria was to tell some close relatives that Ernest was a homosexual.[7][8] Apparently, she had caught her husband in bed with a male servant when, in 1897, she returned home from a visit to her sister Queen Marie of Romania. She did not make her accusation public, but told a niece that "no boy was safe, from the stable hands to the kitchen help. He slept quite openly with them all."[9][10] Victoria later married another first cousin, this time on her mother's side, while Ernest married Eleonore of Solms-Hohensolms-Lich.

Ernest Louis remarried in Darmstadt, on 2 February 1905, to Princess Eleonore of Solms-Hohensolms-Lich (17 September 1871 – 16 November 1937). This marriage proved harmonious and happy. The couple had two sons:

• Georg Donatus, Hereditary Grand Duke of Hesse (1906–1937). He married Ernest's grand-niece, Princess Cecilie of Greece and Denmark, a sister of Prince Philip, Duke of Edinburgh, and had issue. The couple and two of their young sons were killed in a plane crash in 1937, leaving behind a daughter who also died two years later, while yet a child.
• Louis, Prince of Hesse and by Rhine (1908–1968), who married Margaret Campbell Geddes, daughter of Auckland Geddes, 1st Baron Geddes; no issue. Louis adopted Moritz, Landgrave of Hesse as his heir, thereby uniting the two lines of the Hesse family.

In addition to his marriage, Ernest Louis maintained a close friendship with the bisexual Karl August Lingner, the inventor of Odol, one of the first liquid mouth-washes.[11] When Lingner died of tongue cancer, he bequeathed Tarasp Castle in Switzerland to Ernest Louis. However, the Hesse family never lived in it, and it was sold in 2016.