Phillipe's first wife Princess Henrietta of England died on 30 June 1670.
His brother Louis XIV himself looked for a second wife for Philippe, who was eager to have a male heir to continue the Orléans line. Louis rejected many candidates before settling on the Protestant Princess Palatine Elisabeth Charlotte. Known as Liselotte within her family, she was the only daughter of Charles I Louis, Elector Palatine, and his estranged wife Charlotte of Hesse-Kassel. Elizabeth Charlotte had grown up with her aunt Sophia of Hanover due to her parents' bad relationship. The Princess Palatine was Henrietta's first cousin.
On 16 November 1671, she was married by proxy at Metz to Philippe I, Duke of Orléans. By prearrangement, after leaving her father's realm but prior to arriving in France, she formally converted to Roman Catholicism. The arranged marriage was conceived by the bride's aunt, Anna Gonzaga, a close friend of her future husband and his deceased first wife, who negotiated the marriage contract, including the secret Catholic instruction and subsequent public conversion of the fiancée. At the French court, her husband Philippe was known by the traditional honorific of Monsieur.
As his wife, Elisabeth Charlotte assumed the style of Madame. She was not attractive, as Henrietta had been. When Philippe first saw her, he is said to have remarked "how will I ever be able to sleep with her?" Madame de Sévigné noted how popular the new Madame was with the court. She became renowned for her brusque candor, upright character, and lack of vanity. Her letters record how willingly she gave up sharing Philippe's bed at his request after their children's births and how unwillingly she quietly endured the presence of his male favourites in their household.
The couple was very happy in the first years of their marriage. His lover, the Chevalier de Lorraine was in Italy, but returned in spring 1672. Pregnant later that year, Elizabeth Charlotte gave birth to a son in June 1673 who was named Alexandre Louis and given the title Duke of Valois. Alexandre Louis died, however, in 1676. After his death she experienced depression.
A second son, Philippe, followed in 1674, and then a daughter, Élisabeth Charlotte, in 1676. After her birth, the couple mutually agreed to cease conjugal relations. Philippe turned to his minions, and Elisabeth Charlotte to writing.
Elizabeth Charlotte was praised as being a natural mother. Philippe's second son with Elizabeth Charlotte, known as the Duke of Chartres until he inherited the dukedom of Orléans in 1701, later served as Regent of France during the minority of Louis XV. Elizabeth Charlotte acted as a mother to Philippe's children by Henrietta and maintained correspondence with them until their last days.
The homosexual proclivities of her husband were well known at court. Elisabeth Charlotte confided that he needed "rosaries and holy medals draped in the appropriate places to perform the necessary act" with her.
Elisabeth Charlotte objected to money spent on his favourites and the exercise of their influence with him to enrich themselves. She said on the subject: "I could put up with it if Monsieur only squandered his money in gaming, but sometimes he gives away as much as 100,000 francs at one swoop, and all the economies fall upon me and the children. That is not at all pleasant, besides putting me in a position where, as God is my witness, we would have to live entirely on the King's charity, which is a miserable thing."
Elisabeth Charlotte had apartments at Versailles, use of the Palais-Royal in Paris, and her favourite residence, the beautiful Château de Saint-Cloud on the outskirts of Paris, which was the couple's main residence when not at the Palace of Versailles. Liselotte also had an apartment at the King's private residence, the Château de Marly. In her dowager years she would stay at the Grand Trianon built by her brother-in-law.
On 9 June 1701 her husband, just under sixty years old, died of a stroke at the château de Saint-Cloud. Earlier, he had a heated argument with his brother at the Château de Marly about the conduct of his son—who was also the king's son-in-law. After her husband's death, Elisabeth Charlotte feared that the king would send her to a convent, as stipulated in her marriage contract. Instead she was confronted with secretly-made excerpts of her all-too-candid letters to correspondents abroad.
She remained welcome at court. She was allowed to keep her apartments at all the royal residences and retained her rank. From her husband, she inherited 40,000 livres a year. Louis XIV added 250,000 livres, and her son promised her another 200,000.