After an abortive attempt to publish a collection of sonnets, Frédéric began studying law at the same university in 1900, but after earning his degree he gave up the idea of a legal career in order to continue writing, moving to Ixelles and taking employment as a librarian in 1906.

He spent some months in England before travelling to the Côte d'Azur, where he met many famous artists and writers, and fell in love with a married Russian named Maria Marcovna Miloslawski (1893–1947).

He returned with her to Brussels in 1920, the same year he published Mélusine, and married her on 20 July 1925, having divorced Marguerite in 1919.

In 1937 he signed the famous Manifeste du lundi of Charles Plisnier, a denunciation of regionalism.

He reestablished Le Disque vert with René de Soher in 1951, and compiled a collected volume of his poetry in 1959.