In early December 1907, Natalia was introduced to one of her husband's fellow officers in the Blue Cuirassiers: Grand Duke Michael Alexandrovich of Russia, the brother of Tsar Nicholas II. The following month, they met again at the Regimental Winter Ball. From then on, they began to see each other regularly, though Michael was always careful to include Wulfert in his letters and invitations, at least until October 1908, and use the formal form of "you" ("vy") rather than the familiar one ("ty"). Rumours of their affair spread through the regiment, and Wulfert grew resentful. Michael began sending her secret letters to a separate postal address, now writing to her in familiar terms, and Wulfert grew physically violent, as Natalia refused to share his bed. In July 1909, privately in a letter, she accused her husband of rape. She packed luggage, and with their daughter, an elderly female cousin, and two maids, she left Wulfert for a break abroad in Switzerland. Both Michael and Wulfert turned up at the train station to see her off, and Wulfert created a scene by loudly accusing her of ruining him.