Why did Onegin kill Lensky in Pushkin's novel 'Eugene Onegin'?

Why did Onegin kill Lensky?
An evening at Larin's house. Onegin is bored. He is mad at Lensky for bringing him here.
He decides to tease his friend.
He begins to deliberately hit on Olga, Lensky's fiancee.
This deeply offends Lensky and he challenges Onegin to a duel.
Onegin accepts the challenge, frightened by the possible reaction of the high society.
Eugene understands the absurdity of the duel and tries to get it canceled.
He comes late and brings his servant instead of a second.
Still, the duel took place. Onegin hesitates not to shoot for fear of losing his reputation.
Eugene shoots from afar, poorly aimed. He hopes that the shot will not be fatal. But he ends up killing his friend.
The most famous duel in Russian literature turns out to be senseless and tragic.
The young Lensky was killed by feverishness, and Onegin's selfishness and fear of tarnishing his reputation brought him to a sad end.
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[philzmusic]

One could say that Onegin unconsciously hates Lensky because he still has the youthful illusions Onegin has lost, but in the end it remains a mystery, one of those strange things people do without knowing why. It's part of Pushkin's genius that he writes a scene that is illogical, just as real life is. A lesser poet would have given a reason.