Despina chastises Fiordiligi and Dorabella for not knowing how to deal with men. The sisters decide that perhaps Despina is right—there can be no harm in amusing themselves with the handsome strangers. They choose which man they’d like, each picking the other’s fiancée. Don Alfonso brings the girls into the Pleasure Garden to meet the boys again.

In the fairground, Dorabella responds quickly to the disguised Guglielmo’s advances. She accepts a gift and relinquishes her locket with Ferrando’s portrait.

Fiordiligi, however, refuses to yield to Ferrando, although she admits to herself that her heart has been won.

Ferrando is certain that they have won the wager. Guglielmo is happy to hear that Fiordiligi has been faithful to him, but when he shows his friend the portrait he took from Dorabella, Ferrando is furious. Gugliemo asks Alfonso to pay him his half of the winnings, but Alfonso reminds him that the day is not yet over.

Fiordiligi condemns Dorabella for her betrayal and resolves to leave the Pleasure Garden and join her beloved at the front.

Ferrando suddenly appears and declares his love for Fiordiligi with renewed passion. While Guglielmo watches helplessly, she finally accepts. Guglielmo and Ferrando are distraught at their fiancées’ infidelity. Don Alfonso encourages the boys to forgive the women and marry them. After all, their behavior is only human nature.

The sisters have agreed to marry the young strangers, and Despina, impersonating a lawyer, does the honors. Alfonso suddenly announces that Guglielmo and Ferrando have returned from battle. In panic, the sisters hide their intended husbands, who return as their real selves and are horrified to discover the marriage contracts. Finally, the boys reveal the entire charade, and Fiordiligi and Dorabella ask forgiveness. Alfonso bids the lovers learn their lesson.

Synopsis by The Metropolitan Opera