Anna takes Dolly to Princess Barbara, who immediately starts talking in the most condescending and complacent way about doing her duty to keep Anna company. It is not for her to judge the relationship between Vronsky and Anna.
Dolly thinks that Princess Barbara is OK with their adultery simply because of all the comforts she can get out of Anna and Vronsky.
In general, Dolly feels uncomfortable with the company.
They have two hours until dinner, and all sorts of amusements are proposed.
In the end, they tour a hospital that Vronsky is building. He's passionate and proud of it.
During the tour, Dolly sees how Anna could have fallen for him. She is attracted to his excitement and passion.