Elisabeth Christine of Brunswick-Wolfenbüttel, Crown Princess of Prussia

The king may have imagined this to be the first of many children, and looked forward to the birth of an heir, but it was not to be. Already at this time, Elisabeth Christine was having an affair with a musician named Müller. While the musician Müller was sent away without making any fuss, the marriage was on the rocks in a most alarming manner. On his part, Frederick William confirmed to the norms of his day, and considered that his wife should make no fuss if he indulged in casual sex with sundry dancers and actresses, because they could never take her place, and all he wanted from them was a night of revelry. Elisabeth Christine felt otherwise, and took her disagreement to the point of vengeance. The couple were both very young indeed, and both very hot-headed. In the Vertraute Briefe, the marital relationship of Elisabeth Christine is described as follows:

"Frederic William was now twenty-one years of age; his disposition was good, but his capacity was slender; he resembled the Brunswicks in person, being six feet two in height, and proportionally stout. But he was unfortunately addicted to the grossest sensuality, and his time, when not occupied by his military duties, was spent with vile women and other loose companions. His young wife resented this conduct in the highest degree; wounded alike in her wifehood and her womanhood, she not only separated herself from the crown Prince, and haughtily refused him admission to her presence, but, alas! She sacrificed even virtue to revenge."[1]

If the king had very little sympathy for the adultery of men, he had none at all for that of women, least of all when the legitimacy of his own successors may be called into question.[1] The king had little patience for indiscipline or human frailty, and he could hardly understand what moved people to commit adultery. He roundly admonished his nephew for consorting with low women. Elisabeth Christine, supposedly to spite her husband, began having affairs with young officers of the Potsdam Guard, he was. At first, the King treated her scandals leniently, hoping for improvement and wanting to forget everything that had happened. However, as was noted by Friedrich Wilhelm von Thulemeyer,[3] the Crown Princess became pregnant by her lover, a musician called Pietro. By late January 1769 they planned to escape to Italy, but she was betrayed. On a masked ball given by Prince Henry in celebration of the king's birthday on 24 January 1769, the Crown Prince was informed of her affairs by an anonymous person hidden behind a mask, which enraged him despite his own adultery, and made him demand a divorce.[1] Elisabeth Christine's correspondence would have also revealed that she first planned to poison her husband, her brother Prince William of Brunswick (who was involved in the plot) and her uncle the King,[4] and a letter from her to the musician Pietro was also intercepted with the following content: "My dear Pietro, come to Berlin [...]. I can not live without you. You have to kidnap me from here [...]. I would rather eat dry bread than live longer with that fat oaf".[2]

Portrait by Ziesenis

King Frederick was initially unwilling to agree to a divorce, as his sympathy was greater for Elisabeth Christine than for Frederick William, but the Crown Prince insisted in his demand for a divorce, and urged in agreement with the King the annulment of his marriage on grounds to avoid claims of illegitimate offspring on the Prussian throne, to which the Brunswick court agreed.[5] The musician Pietro was arrested and taken to Magdeburg, where he was reportedly beheaded.[6] Elisabeth Christine terminated her pregnancy with drugs.[7] Her brother, Prince William of Brunswick, was aware of her affairs, and his attempts to hide them and defend her exposed him to suspicions that he himself had been involved in them.[1]

The divorce was officially pronounced on 18 April 1769. Only three months after the separation, on 14 July, Frederick the Great forced his nephew to remarry, with Frederica Louisa of Hesse-Darmstadt. In a letter wrote to his sister (and Elisabeth Christine's mother) Philippine Charlotte, the King summarized all the events:

The husband, young and immoral, practiced a debauched life daily; the princess his wife, who was in the prime of her beauty, found herself grossly insulted by the low regard that her own charm had over him. Her vivacity and good opinion of herself, took her to avenge the offenses against her. Soon she found herself in such debauchery that hardly inferior to those of her husband; the disaster broke out and became public.

Elisabeth Christine was firstly banished to Küstrin Fortress and later placed under house arrest as a Prisoner of state in the Ducal Castle of Stettin under the care of her cousin, Duke Augustus William of Brunswick-Bevern. She lost the title of Royal Highness and was given the title of Serene Highness.

At first, she lived in harsh circumstances. Being of an extrovert nature, she suffered from her isolation: reportedly, she sometimes placed all the chairs in a long row in her apartments, and danced "Anglaises" between them to ease her boredom. [1] She did at one point attempt to escape, and made an agreement with an officer to help her escape to Venice, but the plan was never put in fruition as her accomplice suddenly disappeared.[1] Eventually, King Frederick improved her living conditions, and in 1774, she was given a summer residence in the medieval cloister in Jasenitz.

After the death of Frederick the Great in 1786, she received a visit from her former spouse, and during his reign, her conditions improved: she was given permission to entertain visitors, and to walk, and ride on horseback in the areas of the town.[1] According to Mirabeau, she was offered her release, but declined, as she had by that time grown used to her lifestyle.[1] An incident is known, when she slapped an officer who insisted upon opening a New Year's gift from her mother: when he sent a complaint to the king, he answered "no man could ever be insulted by a blow from the hand of so fair a lady."[1]

Elisabeth Christine never saw her daughter or siblings again; during her later life, King Frederick William IV was the only one who visited her. When the French army occupied Stettin in 1806, the so-called Elisabeth of Stettin moved to a small country estate outside the city walls, which she called Landhaus Friedrichsgnade ('Villa Frederick's mercy').

Elisabeth Christine died at the age of 93, having survived her parents, all her siblings, her daughter, nieces and nephews, and her former husband. At her death, all the bells of the city rang. She had a mausoleum built for herself in her beloved park because she didn't want to be buried with her relatives in the Ducal Brunswick Crypt.[8] When the park was handed to private hands, she was reburied in the Chapel of the Ducal Castle of Stettin on the night of 19 July 1849.[9] Other sources, however, indicated that she was later reburied in the cathedral of Kraków.[10]