Olga's Fickle Love
Even though Lensky loves her passionately and writes her verses with outstandingly genuine emotion, Olga is quickly charmed by Onegin and eventually marries a lancer not too soon after her fiance's death. Onegin had pointed out, much to Lensky's displeasure, that Olga was a very conventional sort of girl, not the kind who would be worthy of being a poet's muse.
Onegin's Letter
When Onegin falls deeply in love with Tatyana in Moscow and receives her cold indifference, he becomes driven to the kind of feverish state which she was in when first in love with him. The letter he writes to her begging her for love and the speech which she gives him at the end show their reversed roles.
Onegin's Moralizing Rejection of Tatyana's Love
Even though Onegin believes that he is imparting his experience and goodwill to Tatyana by rejecting her love, he in fact lacks the experience of genuine love and ends up hurting her deeply.
Tatyana's Transformation
For most of the novel, Tatyana is the most dreamy and naive of all the characters, but she matures quickly after deducing Onegin's personality from reading his books and settling into life as a Grande Dame in Moscow. At the end, we find the girl who was once obsessed with French romantic novels more in control of herself and the world around her than any other character.
