Lord Capulet talks in Act I, scene ii with Paris about his love for his daughter. He wishes to shelter her yet from marriage, even though many girls her age are already married with children. He also seems to respect her opinion in choosing a marriage partner, a rare perspective for a father in the day that Shakespeare lived and worked. Wealthy and prestigious families saw marriage as a contract, an alliance between families meant to add prestige or financial strength, and not as a contract based upon love. He says:
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,
And she agreed, within the scope of choice
Lies my consent and fair according voice.
So, Capulet seems to dote on his only daughter and gives her an unconventional voice in her own matchmaking.
And yet the two have no actual interaction until Act III, scene v. This scene comes after Tybalt's death and Capulet's determination that he can cheer his daughter up (She is thought to be grieving over her cousin's death.) by offering her a marriage to Paris. Capulet, through the course of the play, has shown himself to be a somewhat volatile and inconsistent man, so when Juliet refuses his "gift," he explodes in a rage that, in some productions of the play, has him actually physically violent with Juliet. In any event, he tells her to get herself to church and marry Paris or:
Beg! Starve! Die in the streets!
For by my soul I'll ne'er acknowledge thee,
Nor what is mine shall never do thee good.
This is a far cry from the gushing father of Act I, and it is the opposite of the father, once he believes that his daughter is dead in Act IV, who says over her cold body:
Death lies on her like an untimely frost
Upon the sweetest flower of all the field.
So, Juliet's relationship with Capulet is governed and decided by his opinions and actions. She only speaks at two moments to him in the entire play -- the first in Act III when she refuses Paris, and the second in Act IV when she apologizes for this and repents (an action that the audience knows is false). Juliet is not given enough interaction with Capulet to note any sort of "change" in their relationship through the course of the play.
It is Capulet who could be noted to change towards his daughter. And yet, he changes so frequently that it is hard to assign a reason to his change, expect to say that it is because she has displeased him. When Juliet does what he wants, he is a loving, doting father. When she does not, he is cruel and harsh. This may or may not be a result of the events of the play. His actions with others and throughout the play seem to suggest that it is simply his nature to flip-flop, to be swayed by his quick temper and his mood swings. If this is the case, then he doesn't actually change at all.
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I think part of what makes the relationship between Capulet and Juliet so challenging to dissect is because it seems that their relationship reflects most father/ daughter relationships of the time. As a father, Capulet is fairly out of touch with his relationship between he and his daughter because Capulet is more concerned with appearances. He is driven by social prestige and concerned with the name of his family more than he is making sure that his finger is on the pulse of the relationship he shares with his daughter. He does not acknowledge his daughter for anything more than an extension of the family's name, and following suit with the will of the family. When Juliet refuses the marriage to Paris, Capulet demonstrates this with his wrath towards her. His anger towards her is because of the shame she brings in not upholding the family name. Juliet starts off as being a dutiful daughter, but once recognizing that the pull of her own individual freedom is stronger than all else, she breaks from the family and breaks from its wishes. This is a testament to the initial gap that is present between Capulet and Juliet, father and daughter.