A violinist, she met Ravel after giving a performance of his Trio during the First World War. Her first husband, the painter Jacques Jourdan, died during the war. She subsequently became the partner of another artist, Luc-Albert Moreau (1882-1948) who painted realistic scenes of the war, and also made sketches of Ravel and illustrations for the Chansons madécasses.
She described her first encounter with Ravel (who had been in a poor mental and physical state following the recent death of his mother) in 1917: "Enfin, après le concert, je vis venir à moi, timide, balbutiant, un petit homme mince, sec, nerveux, aux cheveux grisonnants, et dont l'oeil pétillant et le nez pointu m'évoquèrent la fine tête d'un renard." (Jourdan-Morhange, , p.18].
She and Moreau bought a house in the early 1920s at Mesnuls, 3 kilometres from Ravel's home at Montfort l'Amaury, and they were among his closest friends during the last two decades of his life. According to Manuel Rosenthal, Ravel proposed marriage to her, and was refused; but she does not mention this in her memoir Ravel et nous, (Jourdan-Morhange )
In a letter in March 1920, Ravel indicated that he was planning to write a violin concerto for her - but that was an unfulfilled project. (Orenstein , letter 167). Ravel dedicated to her the Sonate pour violon et piano, and it was intended that she should give the first performance. But her career was cut short when her hands were afflicted by arthritis.
Her manner was described as cat-like, and Ravel gave her a nickname: "Je ne peux pourtant pas, lui disait-il à l'aube de leur amitié, vous appeler Hélène. A-t-on jamais nommé une chatte Hélène? Vous vous appelez donc Moune, indiscutablement." [Mouni was the name of one of Ravel's favourite Siamese cats.] (Told by Colette in the preface to Jourdan-Morhange, , p.10].