William I of Württemberg
On 24 January 1816, in Saint Petersburg, he married his first cousin, Grand Duchess Catherine Pavlovna of Russia (1788–1819), daughter of Emperor Paul I of Russia (1754–1801) and Princess Sophie Dorothea of Württemberg (1759–1828). The couple had two children:
Maria Feodorovna (Sophie Dorothea of Württemberg)
The close relationship between Paul and Catherine Nelidova, one of Maria's ladies-in-waiting, was the cause of the first crack in their marriage. Paul's liaison, a deeply intense but, according to him, only platonic attachment to Nelidova, was particularly painful for Maria, as the other woman had been her friend. Her relations with Nelidova became very bitter for several years. Later, however, she began to accept Paul's word that it was only a friendship, and eventually Maria not only reconciled with the idea, but joined forces with Nelidova in an attempt to moderate Paul's increasingly neurotic temperament.