Don Pasquale by Gaetano Donizetti

Don Pasquale is a comic opera – an opera buffa – with many implausible plot twists, which eventually lead to a happy outcome for all concerned.
Don Pasquale is a rich, elderly bachelor. His heir, his nephew Ernesto, has refused to marry his uncle’s choice of bride, as he is in love with Norina, a girl of no means. Don Pasquale disinherits his nephew and decides he will marry and produce an heir. His friend, Dr Malatesta, suggests his own sister, Sofronia, as a suitable, modest young wife.
Unbeknownst to Don Pasquale, Malatesta doesn’t have a sister and is, in fact plotting a scheme to enable Norina and Ernesto to marry. Norina will pretend to be Sofronia, will marry Don Pasquale in a fake ceremony and drive him to distraction with her spendthrift and shrewish ways.
Initially, Ernesto is unaware of the scheme; feels betrayed by Malatesta and totally confused when he meets “Sofronia”, although he soon catches on.
“Sofronia” is spending Don Pasquale’s money like water and  tells him he is too old to be seen with her in society. She prefers a young escort like Ernesto. Don Pasquale decides he must divorce his wife, who, he discovers has a secret assignation with a lover.
Norina and Ernesto plays the lovers’ scene in the garden, witnessed by Don Pasquale and Malatesta. Ernesto escapes but Norina/ “Sofronia” is confronted by her “husband” who now definitely wants a divorce, agreeing with Malatesta that “Sofronia” must make way for Ernesto’s bride, Norina. Don Pasquale will make a handsome marriage settlement on Ernesto, a price worth paying to rid himself this dreadful wife.
Ernesto appears, Norina’s identity is revealed and Don Pasquale, relieved he is not actually married to “Sofronia”, blesses the young couple.