I think she's thinking about the shit that's going on in her marriage the problems with the husband the doubts if he is having an affair or not the sexual frustration that Anna feels every time she expected a good fuck with her husband and is disappointed again the pressure at work the desires she is feeling thinking about other guys and etc... You can see the anxiety and frustration mixed in on her face.
She needs a good fuck that's the first thing her body wants lol even though she feels guilty at times that she masturbated and thought about someone it's evident that she really needs to get laid