Black Knight challenges Minstrel

Milton Cross narrates a ballet story at the Ballet de France. The tale involves a girl and a minstrel whose relationship is disrupted by the sorrowful countenance, the official fiancé of the Princess. The Black Knight, envious of the minstrel's success in winning the Princess's heart, challenges him to a duel.

What event interrupts the idol of the girl?

Describe the emotional state of the girl in the story.