Jane is relieved to find that Mrs. Fairfax is in fact a nice lady, and that she does not own Fairfield. Perhaps she wants to live as an equal, or maybe she is tired of having authority figures looking over her, as they have done for her entire life.
The writer does not develop the statement in the first sentence; rather the discussion fizzles out into speculation with no specific reference to the text.
In an expository essay especially, you may be able to refer to objective support for your position; if you are writing a paper about birth control, you might find it useful to include statistical information to strengthen your argument. Never state without supporting evidence; aside from the problem of proof, you will end up with a short essay.