As for me I say that those who are tormented in hell are tormented by the invasion of love. What is there more bitter and violent than the pains of love? Those who feel they have sinned against love bear in themselves a damnation much heavier than the most dreaded punishments. The suffering with which sinning against love afflicts the heart is more keenly felt than any other torment. It is absurd to assume that the sinners in hell are deprived of God's love. Love is offered impartially. But by its very power it acts in two ways. It torments sinners, as happens here on earth when we are tormented by the presence of a friend to whom we have been unfaithful. And it gives joy to those who have been faithful. That is what the torment of hell is in my opinion: remorse. But love inebriates the souls of the sons and daughters of heaven by its delectability.
-St Isaac of Nineveh
as I recall, Dostoevsky's Father Zossima said much the same thing in The Brothers Karamazov.