There’s no reason for Onegin to turn down Tatyana’s Love, but he refused only because he’s depressed. Onegin’s depression is not just his own, it also belongs to the Russian aristocratic intellectuals of that time. Therefore, Onegin’s love tragedy is essentially the tragedy of Russian aristocratic intellectuals. Onegin is not morally perfect, but because in a historical and inevitable way to the destruction, so it’s more tragic than the morally perfect Lensky and should be the hero of tragedy.