Act 2 synopsis from Tchaikovsky's Eugene Onegin, a la wikipedia (emphasis mine)
Scene 1: The ballroom of the Larin house
Tatyana's name-day party. Onegin is irritated with the country people who gossip about him and Tatyana, and with Lensky for persuading him to come. He decides to revenge himself by dancing and flirting with Olga. Lensky becomes extremely jealous. Olga is insensitive to her fiancé and apparently attracted to Onegin. There is a diversion, while a French neighbour called Monsieur Triquet (tenor) sings some couplets in honour of Tatyana, after which the quarrel becomes more intense. Lensky renounces his friendship with Onegin in front of all the guests, and challenges Onegin to a duel, which the latter is forced, with many misgivings, to accept.
Scene 2: On the banks of a wooded stream, early morning
Lensky is waiting for Onegin, and sings of his uncertain fate and his love for Olga. Onegin arrives. They are both reluctant to go ahead with the duel but lack the power to stop it. Onegin shoots Lensky dead.
Sing, Lensky, sing!
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