Anna seems completely natural and relaxed, but Karenin feels like she's closed her soul to him.
She makes fun of his concern over the propriety of her behavior with Vronsky.
Anna thinks to herself that the only reason he cares is because her relationship to Vronsky was noticed in public. In other words, she doesn't think that her husband cares about her feelings and their marriage as much as he cares about what society thinks of them.
Karenin continues to lecture her, and Anna complains of being sleepy. All the while she keeps her tone light and sweet.
Karenin tells her that he loves her, brings up their son, and says that to break these bonds would call down serious punishment from God. (This is all different from his prepared speech, by the way.)
Anna thinks to herself that Karenin doesn't know what love is. Karenin pleads that, if there is anything to this whole thing with Vronsky, that she tell him. Anna refuses to confess any feelings towards Vronsky, and they fall silent.
They go to bed.
Karenin falls asleep quickly, but for a long time Anna stays awake thinking of Vronsky: "her heart filled with excitement and criminal joy" (2.9.32).