Their stay in Petersburg was the more painful to Vronsky that he perceived all the time a sort of new mood that he could not understand in Anna.

At one time she would seem in love with him, and then she would become cold, irritable, and impenetrable.

She was worrying over something, and keeping something back from him, and did not seem to notice the humiliations which poisoned his existence, and for her, with her delicate intuition, must have been still more unbearable.