"Go to her, sir; own your fault again. Maybe God will aid you. She is suffering so, it's sad to see her; and besides, everything in the house is topsy-turvy. You must have pity, sir, on the children. Beg her forgiveness, sir. There's no help for it! One must take the consequences..." (1.2.30-31)
The children's nurse urges Oblonsky to throw himself at his wife's mercy for the sake of the children. Oblonsky eventually agrees, which provides and interesting contrast to Anna's later behavior – she does not save her marriage for the sake of her son.
"But if it is repeated?"
"It cannot be, as I understand it..."
"Yes, but could you forgive it?"
"I don't know, I can't judge.... Yes, I can," said Anna, thinking a moment; and grasping the position in her thought and weighing it in her inner balance, she added: "Yes, I can, I can, I can. Yes, I could forgive it. I could not be the same, no; but I could forgive it, and forgive it as though it had never been, never been at all..."
"Oh, of course," Dolly interposed quickly, as though saying what she had more than once thought, "else it would not be forgiveness. If one forgives, it must be completely, completely. Come, let us go; I'll take you to your room," she said, getting up, and on the way she embraced Anna. "My dear, how glad I am you came. It has made things better, ever so much better." (1.19.50)
Anna argues that she could forgive repeated infidelity, and would forgive it as though it never happened. Dolly replies that that's the only kind of forgiveness there is. But do you believe Anna? Maybe she could forgive Karenin if he were unfaithful to her, since she doesn't love him anyway. But could she forgive Vronsky if he cheated on her? After all, in the last parts of the novel, Anna is consumed with jealousy over Vronsky. What do you think?
"My God! Forgive me!" she said, sobbing, pressing his hands to her bosom.
She felt so sinful, so guilty, that nothing was left her but to humiliate herself and beg forgiveness; and as now there was no one in her life but him, to him she addressed her prayer for forgiveness. Looking at him, she had a physical sense of her humiliation, and she could say nothing more. (2.11.4-5)
After she sleeps with Vronsky, Anna begs God for forgiveness, and then, feeling that there's no one in her life but Vronsky, addresses her plea for forgiveness to him. Why doesn't Anna ask Karenin for forgiveness? Why Vronsky instead?
[Dolly:] "No, wait a minute. You must not ruin her. Wait a little; I will tell you about myself. I was married, and my husband deceived me; in anger and jealousy, I would have thrown up everything, I would myself.... But I came to myself again; and who did it? Anna saved me. And here I am living on. The children are growing up, my husband has come back to his family, and feels his fault, is growing purer, better, and I live on.... I have forgiven it, and you ought to forgive!"
Alexey Alexandrovitch [Karenin] heard her, but her words had no effect on him now. All the hatred of that day when he had resolved on a divorce had sprung up again in his soul. He shook himself, and said in a shrill, loud voice: –
"Forgive I cannot, and do not wish to, and I regard it as wrong. I have done everything for this woman, and she has trodden it all in the mud to which she is akin. I am not a spiteful man, I have never hated anyone, but I hate her with my whole soul, and I cannot even forgive her, because I hate her too much for all the wrong she has done me!" he said, with tones of hatred in his voice. (4.12.41)
While Dolly was able to forgive her cheating husband and move on with her life, Karenin is adamant here that he lacks the capacity to forgive all the wrong that Anna has done to him.
"You can't forgive me," [Levin] whispered.
[Kitty:] "Yes, I forgive you; but it's terrible!"
But his happiness was so immense that this confession did not shatter it, it only added another shade to it. She forgave him; but from that time more than ever he considered himself unworthy of her, morally bowed down lower than ever before her, and prized more highly than ever his undeserved happiness. (4.16.34)
Kitty's forgiveness of Levin's past indiscretions only inflames his love for her. Tolstoy paints Kitty as virtuous woman because she has the capacity to forgive. Similarly, when Karenin forgives Anna (see 4.17.39), we the readers and Tolstoy consider him to be a good man.
[Karenin:] "But I saw her and forgave her. And the happiness of forgiveness has revealed to me my duty. I forgive completely. I would offer the other cheek, I would give my cloak if my coat be taken. I pray to God only not to take from me the bliss of forgiveness!"
Tears stood in his eyes, and the luminous, serene look in them impressed Vronsky.
You may trample me in the mud, make me the laughing-stock of society, I will not abandon her, I will never say a word of reproach to you. (4.17.52-54)
Karenin's moment of forgiveness is his highest moment in the novel. Interestingly, forgiving Anna is more important for Karenin than it is for Anna. He feels "bliss" when he finally let's go of his anger at her. Karenin's Christian willingness to forgive (Karenin uses Jesus' instructions to his followers to turn the other cheek in the Gospel of Matthew) is genuine while it lasts. But it doesn't last forever. For more on Karenin's moment of forgiveness, check out Karenin's "Character Analysis" and our discussion on "What's Up with the Epigraph?"
"Not you it was performed that noble act of forgiveness, at which I was moved to ecstasy, and everyone else too, but He, working within your heart," said Countess Lidia Ivanovna, raising her eyes rapturously, "and so you cannot be ashamed of your act." (5.22.13)
Countess Lydia describes religion in overblown ways, but her actions do not match her rhetoric.
It is true that the erroneousness and shallowness of this conception of his faith was dimly perceptible to Alexey Alexandrovitch, and he knew that when, without the slightest idea that his forgiveness was the action of a higher power, he had surrendered directly to the feeling of forgiveness, he had felt more happiness than now when he was thinking every instant that Christ was in his heart, and that in signing official papers he was doing His will. But for Alexey Alexandrovitch it was a necessity to think in that way; it was such a necessity for him in his humiliation to have some elevated standpoint, however imaginary, from which, looked down upon by all, he could look down on others, that he clung, as to his one salvation, to his delusion of salvation. (5.22.26)
Although Karenin knows that his spontaneous forgiveness was more powerful than Countess Lydia's brand of religion, he embraces her approach anyway because he needs something to which he can cling. Head to Karenin's "Character Analysis" to learn more about his adoption of Countess Lydia's religious approach.
He asked for supper, and began telling her about the races; but in his tone, in his eyes, which became more and more cold, she saw that he did not forgive her for her victory, that the feeling of obstinacy with which she had been struggling had asserted itself again in him. He was colder to her than before, as though he were regretting his surrender. And she, remembering the words that had given her the victory, "how I feel on the brink of calamity, how afraid I am of myself," saw that this weapon was a dangerous one, and that it could not be used a second time. And she felt that beside the love that bound them together there had grown up between them some evil spirit of strife, which she could not exorcise from his, and still less from her own heart. (7.12.20)
Anna and Vronsky's relationship becomes increasingly embittered – there's a distinct lack of forgiveness in both of their hearts. This is in contrast to other relationships that we see, such as Dolly's forgiveness of Oblonsky, and Kitty and Levin's compassion for one another.