For Vronsky, there is no alternative but death. Karenin to a duel and act upon his own intentions. Nikolai, on the other hand, faces death with both hope and hesitation. Death, in this novel, has taken many forms. They are in a place where they feel they have no alternative.
Death is their revealer.
Her trouble would come to an end with the end of her life. Death would be her mercy. For Vronsky, there is no alternative but death. Karenin to a duel and act upon his own intentions. They are in a place where they feel they have no alternative.