From 1885, Știrbei applied for naturalization as a French citizen, which he obtained in 1888. In 1895, he married Simonin. He took personal care of his adoptive daughters' training in art, allowing them to study with Léon Comerre and Ferdinand Roybet. He also bought India and Sweden–Norway's pavilions from the 1878 World's Fair (respectively designed by Caspar Purdon Clarke and Henrik Thrap-Meyer), which became their respective studios.