Her father is more interested in seeing that she marries well and soon rather than her personal happiness. He tells Paris that although she is "free to choose" her own mate, it must be from a narrow pool that he has approved of, and what's more, he has already selected Paris. He sees no reason why his daughter would object.
In 3.5, Lady Capulet believes Juliet is weeping for Tybault. She is suprised by the reaction and more or less tells her to get over it, she looks stupid. Not exactly a kind response! (Not to mention off-base.)
She says:
"Evermore weeping for your cousin's death?
What wilt thou wash him from his grave with tears?
And if thou couldst, thou couldnst not make him live.
Therefore have done: some grief show much of love,
But much of grief shows stills some want of wit." (3.5.70-73)
Her refusal to marry Paris meets with anger, not understanding. She sees no reason why such a match would not "happily make thee a joyful bride," but when Juliet protests, Lady Capulet exasperatedly tells her that she'd better take it up with her father: "Here comes your father now, tell him so yourself / And see how he will take it at your hands" (3.5.124-125).
She doesn't truly side with anyone, but it is clear she is not much on her daughter's side.
The loyalty that Romeo and Juliet feel toward their parents lies at the root of their dilemma. It's called filial duty. In the medieval world of Verona, as well as in Elizabethan England, this duty was more than just being respectful and doing chores around the house. Parents, and fathers in particular, were entirely in charge of their children. There was generally no