William Shakespeare's Romeo and Juliet is a story about two feuding families: the Montagues and the Capulets. Thirteen-year-old Juliet is a Capulet, and in the beginning she has no particular desire to get married and is willing to do what her parents ask her to do. Her parents are not pushing her to get married, either. When Paris asks Capulet if he can marry Juliet, Capulet is not particularly interested because she is his only child and he wants to be sure she is happy.
The earth hath swallow'd all my hopes but she,
She is the hopeful lady of my earth:
But woo her, gentle Paris, get her heart,
My will to her consent is but a part;
An she agree, within her scope of choice
Lies my consent and fair according voice.
It is significant to note here that he says he will never consent to any suitor who has not wooed and won Juliet's heart. Her consent will weigh heavily when he gives his own consent. That will change in a matter of days.
On the night of the famous Capulet party, Juliet's mother asks Juliet how she feels about getting married; Juliet says it is something she has not much thought about. Her mother tells her that Paris is interested in Juliet and asks her daughter to look at him tonight at the party with an open mind, since it many other girls (including herself) are already married at this age. Juliet agrees, saying:
This is true obedience, as she not only says she will look as asked but she will not overstep her position as a daughter and take any action on what she sees.
Everything changes in the relationship between the Capulets and their daughters because of two things: first, Juliet meets Romeo, and second, Tybalt is killed. Hours after she meets Romeo, Juliet marries him. Though her parents do not know it yet, this causes an insurmountable rift in their relationship with Juliet. Once she was modest and obedient; now she is headstrong and dismissive of her parents' authority.
Once Romeo kills Tybalt, the relationship between Juliet and her parents is irrevocably broken. While Juliet mourns the loss of Romeo who has been banished, her parents assume she is inconsolable over the loss of Tybalt. Their failure to communicate openly on this key issue causes all the other problems in the play. Presumably because he wants to help ease his daughter's grief, he plans her hasty marriage to Paris--a complete reversal of his previous vow. Because she refuses, he is angry enough to hit her and disown her.
This dramatic turnaround for Capulet is explainable only by his grief and, ironically, his desire to help his daughter deal with her grief. If not that, then Capulet is simply a capricious and double-minded man. Things change again once he realizes he has lost his daughter over a ridiculous feud.
In the midst of all this dramatic and hasty change, Juliet looks to the Nurse as her primary adviser, and of course the Nurse acts on emotion rather than reason both in helping Juliet marry Romeo and then in advising Juliet to marry Paris since Romeo has been banished. In both cases, the Nurse serves as a bad adviser to Juliet.