How does Gurov change after leaving Anna?

The classic short story "The Lady With the Pet Dog" by Anton Chekhov tells of a man and a woman who meet while vacationing in Yalta. Dmitri Gurov is a banker in the midst of an unhappy marriage. He is used to picking up women and having brief affairs with them. He does not respect any of them, referring to them as "the lower race." Anna Sergeyevna has come to Yalta without her husband, so her marriage is obviously not going well either. The two have an affair together, and when it's time to leave, they expect to never see each other again.
The change that takes place in Gurov is due to the fact that, without realizing it at first, he has fallen in love with Anna. Unlike all the other women he has spent time with and then left, he cannot forget Anna. He thinks of her constantly.

Anna Sergeyevna did not visit him in dreams, but followed him about everywhere like a shadow and haunted him.

The thought of her obsesses him, and it bothers him that he has no one he can confide in and tell about his feelings for her. He resolves to find her in her hometown. When he does, she confesses that she has been thinking about him too, and they recommence their affair.