Why isn't Megan Fox going to be in transformers 3?

There are a number of rumors, but the two most popular is that Bay fired Fox after she compared him to Hitler not to mention repeatedly speaking ill of both Bay and the film series during interviews, also rumours that she was being very difficult to work with on the set of this film. The other popular rumour is that Megan Fox quit the film because Michael Bay has a reputation for being harsh on set. Now Shia Labouf has confirmed that Fox voluntarily left the series because she was uncomfortable with becoming a "sex object" and didn't like the way that Bay filmed her.