I find that the various adaptations of the Liza Marklund books, including this one, tend to be oversimplified to allow the film to be placed into a 90 minute time slot.
The result is that the character development is weak, and the plot often simplified over what is depicted in the book.
Of course, all film adaptations suffer from simplification for time reasons, but I find particularly with the Marklund books that this seriously detracts form the original work.
For some reason, while Studio Sex is the first Bengtzon book chronologically (not in published order) by Marklund, it is not the first in the sequence of films, and thus we find Annika already married with two children (she was not in the book), and miss totally the development of her character before she was married and thus understand more clearly why she has some mental instability and is so driven by her career.