The young duchess was very beautiful, intelligent, eloquent and educated in philosophy and history. She fell in love with Finnish general Gustav Armfelt, her mother's lover and her tutor. The secret relationship with a much older and married Armfelt resulted in the birth of an illegitimate daughter named Adelaide Gustava Aspasia (nicknamed "Vava"), who was born in secrecy in Hamburg on 13 January 1801. The delivery was traumatic, and, due to an incompetent midwife, she lost the ability to have further children. Wilhelmine gave up her child to one of Armfelt's relatives in Finland and never saw her again. Wilhelmine greatly regretted this decision as time went on. To protect her reputation, Armfelt organized a marriage for her with an émigré French nobleman, Prince Louis de Rohan-Guémenée (1768–1836), the son of the Princesse de Guéméné, the original governess of the children of King Louis XVI of France. The marriage did not last and ended in divorce in 1805.