What is the role of the female model in Balzac’s story? What role does Gillette play in the relationship between Frenhofer and Poussin?

In Honoré de Balzac’s “The Unknown Masterpiece,” Gillette is the mistress of the artist Poussin. Although she plays a central role, her desires are subordinated to those of the male artists, including her lover.
Gillette is presented as an extremely romantic person, so obsessed with love that she resents Poussin’s devotion to his art. The plot complications around her role involve another, rival artist, the very well established and respected Frenhofer, whom it seems Poussin is eager to impress. Poussin proposes that Gillette model for the older man’s planned portrait of a courtesan.
After some demurring, Frenhofer agrees to use her and she goes to the studio. Later, when Poussin and another artist arrive at the studio, it becomes clear that the “master” is not just in decline but near collapse. He has heaped so much paint onto his canvas that the female figure beneath it has disappeared. Gillette, neglected, has become hysterical and upset with Poussin. After they leave, Frenhofer falls apart and destroys his paintings.