Harsher in Hindsight: The circumstances of Lensky's death are alarmingly similar to those of the author's own: both are poets who got shot in a duel with a man who tried to seduce their beloved (fiancée in Lensky's case and wife in Pushkin's case).
Awesome Music: It's Tchaikovsky, after all. Special mention to Tatyana's letter aria, though.
Ho Yay: Onegin and Lensky in some productions. In fact, Krzysztof Warlikowski's production at the Bayerische Staatsoper reimagines the opera in a Brokeback Mountain style, with Onegin portrayed as a gay man, with Lensky as his lover.
Jerkass Woobie: Yes, Onegin was kind of a jerk, but it's hard not to feel sorry for him by the time Act III rolls around.
Tear Jerker: The whole opera, really. It's a story about mistimed love and passion, shattered innocence, and Tchaikovsky's music just serves to highlight all the sadness and pain of the opera.
The Woobie: Lensky could qualify. The poor guy gets his naive and idealistic views about love shattered when Onegin flirts with Olga repeatedly, then ends up killed by Onegin in a duel.