Death embodies hope, solution, desire, and cowardice. One would expect that man would fight against death and do all possible to ward it away from his being, yet, in Anna Karenina the characters welcome it. This reversal shows the desperation of the characters situations. They are in a place where they feel they have no alternative. Their true despair is uncloaked as each goes toward death.
Death is their revealer.
Karenina are the components that highlight the central theme of death. 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.