Princess of Monaco
The marriage ceremony took place 15 June 1757 in Genoa per procura without the groom present. Maria Caterina came to Monaco by boat accompanied by a suite of the Genovese nobility. When they arrived, however, Prince Honoré did not come aboard the ship to welcome his bride. When they asked him to do so, he replied that his status as a monarch demanded that she come to him instead. The Genovese entourage answered that Maria Caterina, was a member of a ruling family of the Republic of Genoa (her uncles, Gian Francesco and Rodolfo Brignole-Sale, held the dogeship in, respectively, 1746–48 and 1762–64). and refused to do so. The ship was therefore stranded offshore for several days, until the predicament was resolved by the couple meeting halfway on a bridge between the boat and the shore.
The relationship was at first amicable, and the couple had two sons, Honoré IV, Prince of Monaco (born 17 May 1758) and Prince Joseph (born in 1763). Maria Caterina was described as beautiful and charming and, initially, as truly in love with her spouse.
Honoré III was however not satisfied with his life in Monaco, where the political issues were managed by his uncle the Chevalier de Grimaldi, and in the summer of 1760, he left for Paris and left Maria Caterina behind. When he eventually allowed her to join him in Paris, the marriage deteriorated, with Honoré spending more and more time with his mistress in Normandy. Maria Caterina attended the French royal court and high society life, but was described as an introverted personality who preferred to sit with the elderly during the balls rather than to dance and who did not use make up, but also considered a great beauty. Maria Caterina lived in Matignon, where she spent her days with the Prince de Condé, Louis Joseph de Bourbon, and seldom took part in court life. Honoré became more and more jealous, and demanded that she write down her thoughts for him. Once, she was alone for several hours with a handsome nobleman, who helped her to open a cupboard which had been stuck.
In 1765, it attracted attention in Paris that she was courted by the Prince of Condé, her spouse was informed by his brother's wife Marie Christine de Rouvroy, he returned from his own adultery in Normandy to scold her: when he left, Maria Caterina, who until then had regarded Condé as merely a friend, reportedly responded to Condé's feelings, and they became involved in a love affair. Honoré III and Maria Caterina lived separate lives with their own lovers, and he did not bring her with him during his state visit to London in 1768. By 1769 she had begun to set up a home in the Hôtel de Lassay, an annex of the Prince de Condé's primary residence in Paris, the Palais-Bourbon.
In 1769, Honoré III, who was informed of Maria Caterina's adultery, responded by returning to Paris and openly flaunted his lovers and his adultery, upon which Maria Caterina left Paris to seek asylum in the convent of Visitation in Le Mans under the protection of her uncle, who was the bishop there. Mediation by her mother brought about a temporary reconciliation, but when her father died and left his fortune to his daughter on the condition that her husband should have no access to it, Honoré III threatened to have her sent back to Monaco, upon which Maria Caterina again sought asylum in Le Mans.
