The scene where Juliet tries to explain to her father why she does not want to marry the Count Parris helps to show what kind of a relationship Lord and Lady Capulet have. Lady Capulet seems to be a somewhat afraid of her husband's temper, and rightly so given how out of control he becomes a moment later, when she tells Juliet that Juliet can tell him herself that she rejects the marriage he has negotiated for her to County Paris, "And see how he will take it at [her] hands" (3.5.130). At first, she seems to sort of abandon her daughter to her husband's anger, telling him that "[She] would the fool were married to her grave" since Juliet has chosen to be disobedient (3.5.145). It seems like she is trying to show him that she sides with him, perhaps, again, because she fears his wrath if she should disagree. This hardly seems to be a sign of a loving relationship.
However, Lord Capulet explodes, shouting and threatening his daughter, prompting his wife to chastise him, saying, "Fie, fie, what, are you mad?" and telling him, "You are too hot" (3.5.163, 186). Even she seems shocked by the violence of his temper and tries to get him to calm down, to see reason. But to no avail; he rages on, threatening Juliet in the meanest way, telling her she can "hang, beg, starve, die in the streets" if she does not obey him (3.5.204). At this point, when Juliet tries to appeal to her mother, Lady Capulet says, "Talk not to me, for I'll not speak a word. / Do as thou wilt, for I have done with thee" (3.5.214-215). Lady Capulet's vacillation here seems to indicate that she fears her husband and his anger more than she loves or feels loved by him. She struggles with how best to respond, how best to contain his anger without redirecting it toward herself. It helps to show how she struggles in her marriage, and could indicate that she is involved in a marriage in which she had little choice, just like her husband tries to do to Juliet.