The two sisters look at pictures of their _ ancés and rhapsodize about them. They can hardly wait to see Ferrando and Guglielmo again. But instead of the two young men, they find Alfonso waiting for them, who tells the women that Ferrando and Guglielmo have been called up and must leave immediately. Desperate, the women take their leave. The game has begun.
Fiordiligi and Dorabella give in to their pain. Even Despina cannot console them – she lectures the women about how men do not deserve _ delity. Alfonso bribes Despina. She is supposed to help him bring two »exotic-looking« strangers into the sisters’ house. As soon as the men arrive, events spin out of control: Dorabella and Fiordiligi are accosted with declarations of love. However, Fiordiligi rejects the strangers with a speech about female steadfastness. Ferrando and Guglielmo are convinced that they have already won the bet. But Alfonso knows that the game is not over yet.
In a suicide scene grandly staged for the two sisters, the strangers pretend that they want to kill themselves out of love for them. Pity for the strangers begins to stir the hearts of the women. After Despina, disguised as a doctor, has brought the supposedly dying men back to life, they once again pursue the women.
Despina provokes Fiordiligi and Dorabella with her views on how con_ dent women ought to behave when dealing with men. The sisters begin to play with _fire in their minds; it turns out that both have long made their decision regarding the two strangers. Dorabella yields to the stranger after hesitating just brie_fly. Fiordiligi, on the other hand, battles her secret desire and initially turns the stranger down.
Ferrando, despite his pain and anger over Dorabella’s in_ delity, must admit to himself that he still loves her. Despina praises Dorabella, who has done the right thing from Despina’s point of view. Fiordiligi is completely distraught by her own emotions. But ultimately, neither can she resist temptation any longer, and succumbs to the stranger. Now Guglielmo, who has been watching Fiordiligi, is also angry and distraught. Alfonso tries to comfort the two confused and hurt lovers with a realistic view of life and love. Women simply cannot help themselves. Così fan tutte!
Then, preparations are made for a double wedding. Despina, now as a notary, has the women sign the wedding contract, when suddenly military music is heard. Fiordiligi and Dorabella are terri_ ed of facing their _fiancés. Ferrando, Guglielmo and Alfonso reveal the game. Alfonso urges the couples to reconcile and forgive each other. The two couples face an uncertain future.