Query: What was the name of Liszt's mistress?
Context: Most biographers of Chopin state that after this the two had little to do with each other, although in his letters dated as late as 1848 he still referred to him as "my friend Liszt". Some commentators point to events in the two men's romantic lives which led to a rift between them; there are claims that Liszt had displayed jealousy of his mistress Marie d'Agoult's obsession with Chopin, while others believe that Chopin had become concerned about Liszt's growing relationship with George Sand.