How does Don Pasquale end?

In the final act of Gaetano Donizetti’s opera Don Pasquale, the titular character’s elaborate scheme to marry and disinherit his nephew, Ernesto, reaches its conclusion through a series of deceptions orchestrated by Dr. Malatesta.12

After Pasquale is driven to desperation by the erratic and spendthrift behavior of his supposed new wife, "Sofronia" (who is actually Norina in disguise), he agrees to a plan to catch her in an act of infidelity in his garden. During the confrontation, Malatesta reveals the truth: the marriage was a sham, and "Sofronia" is actually Norina.1

Stunned but ultimately relieved to be free of the marriage, Pasquale forgives the couple. He grants his blessing to the union of Ernesto and Norina, and the characters conclude the opera by acknowledging the moral of the story: it is foolish for an elderly man to marry.1