Clara Elisabeth von Meysenbug schenkte ihrem herzoglich-kurfürstlichem Geliebten insgesamt zwei Kinder: den Sohn Ernst August (1674-1726) und die Tochter Sophie Charlotte (1675-1725).
"The Countess [Clara (oder Klara) Elisabeth von Meysenbug] was polite to servility to all who were greatly her superiors, but to those whom she considered beneath her, she was intolerably arrogant, proud, and over-bearing. She was, besides, very revengeful, cruel, and insincere, and left no art untried to injure those who had once offended her." (in: Robert Folkestone Williams: Memoirs of Sophia Dorothea, Consort of George I, Vol. 1, London 1845, p. 165).
Wie wir den Aufzeichnungen der Hofdame von Sophie Dorothea von Braunschweig-Lüneburg, Eleonore von dem Knesebeck, entnehmen können, hatte sich Clara Elisabeth von Meysenbug, die Gräfin von Platen, in den schönen Philipp Christoph von Königsmarck verliebt: "One year, during the carnival, among other diversions, there was given a ball, which was attended by the court. On this occasion, young Königsmark exhibited such astonishing skill and expertness in dancing, that he excited the admiration of everybody, and of the Countess Platen in particular. She did not hesitate to go up to him before all present, and to pay him the highest compliments on his performance, declaring that she was surprised and fascinated, and begging him, when the assembly was over, to call upon her. This her command was the more agreeable, because he hoped in the house of Countess Platen to pick up something with which he could afterwards entertain and divert our Princess [Sophie Dorothea von Braunschweig-Lüneburg]. When the Countess Platen found herself alone with him in her house, she revealed her passion to him without reserve, and at the same time employed such allurements that he, a young man, fond of pleasure, and not scrupling to enjoy it, was ready in all things to comply with her wishes. He made no secret of this to the Princess when he next came to see her ..." (in: Robert Folkestone Williams: Memoirs of Sophia Dorothea, Consort of George I, Vol. 2, id., pp. 421-422). Für Königsmarck bedeutete seine sexuelle Beziehung mit der Hauptmätresse des Herzogs Ernst August von Braunschweig-Calenberg, des zukünftigen Kurfürsten von Hannover, nichts. In einer Abendgesellschaft in Dresden, auf der zu viel getrunken wurde, prahlte er über sein Verhältnis mit der Gräfin von Platen: "... Königsmark went to Saxony, to the Elector, the present King Augustus, upon business of his own. The indiscretion which attached to this Count, as to all young men, impelled him publicly, in presence of many gentlemen and the Elector of Saxony, to boast of what had passed between him and Countess Platen ..." (in: Robert Folkestone Williams: Memoirs of Sophia Dorothea, Consort of George I, Vol. 2, id., pp. 427). Selbstverständlich erfuhr Letztere von dieser Peinlichkeit durch ihre vielen Spione, die sie überall hatte. "I [Eleonore von dem Knesebeck] have forgotten to mention the reason why Countess Platen was displeased with Königsmark, before she received those accounts from Saxony. He observed to her one day that she was pregnant by him, because her husband had been absent above a year, at Vienna, ... it is true, from the apprehension that this affair might prejudice her honour and prosperity as well with the Elector as with her husband, for Königsmark procured her a sure remedy for ridding her of this burden. As her condition could not be kept so secret but that remarks were made on her connexion with Königsmark, in which the Electoral Princess [Sophie Dorothea von Braunschweig-Lüneburg] joined, she proposed to Königsmark, in order to dispel the suspicion which was thrown upon them both, to marry her daughter, which Königsmark declined, alleging that he was not capable of committing incest. This tenderness of conscience Platen took highly amiss, and therefore conceived a violent hatred for him, though she had loved him to distraction before his journey to Saxony. When this speech of his had completely kindled her revenge, she was continually intimating to the Elector, that he ought to get rid of Königsmark, who had not merely presumed to promulgate such prodigious lies to the prejudice of her honour; but also for the discovery of the truth in regard to the Electoral Princess, since it seemed more than certain that he had so dishonoured the court of the Elector, that nothing short of his blood was capable of washing away the disgrace." (in: Robert Folkestone Williams: Memoirs of Sophia Dorothea, Consort of George I, Vol. 2, id., pp. 427-428).