When Ella asks Hattie why she hates her, how does she know Hattie is telling the truth? What reasons does Hattie give for hating Ella?

When Ella asks Hattie why she hates her, she knows that she is telling the truth because Ella had slipped a flower into Hattie's bouquet which, when sniffed, forces people to speak truthfully. Hattie tells Ella that she hates her because she is jealous of Ella's looks and bravery, and because Ella does not admire her.