She was the wife of the Belgian Minister of Justice Albert Lilar and mother of the writer Françoise Mallet-Joris and the art historian Marie Fredericq-Lilar.

Applying a strong intellect to her work through precise language, she was a thoroughly modern writer and feminist who nonetheless remained highly versed in many areas of traditional western thought (Encyclopædia Britannica).

She later became a playwright with Le Burlador (1946), an original reinterpretation of the myth of Don Juan from the female perspective that revealed a profound capacity for psychological analysis.

Soixante ans de théâtre belge (1952), originally published in New York City in 1950 as The Belgian Theater since 1890, emphasizes the importance of a Flemish tradition.

Transcendence and metamorphosis are central to her seminal work Le Couple (1963), translated in 1965 by Jonathan Griffin as Aspects of Love in Western Society.