 Duke Paul Frederick married in Schwerin on 5 May 1881 his cousin, the Austrian born Princess Marie of Windisch-Graetz, the daughter of Prince Hugo of Windisch-Graetz and his wife Duchess Louise of Mecklenburg-Schwerin.The couple who had five children who were all raised Roman Catholic, the religion of Princess Marie, lived a quiet life in Venice.While in Venice the family befriended Cardinal Sarto (later Pope Pius X) who often visited the family and acted as a spiritual advisor for them.