...of their behaviour.
Lizzy looks forward to dancing with a man who regards her as good enough to converse and dance with.
Outwardly, Wickham is affable and charming; Darcy remains aloof.
Lizzy may simply expect to see a confirmation at the ball of what she told Wickham- Darcy is not liked by Meryton people. (ch.16)
Yet at Bingley's house, I doubt Lizzy expects any confrontation or argument by them.