Lady Capulet does not know Juliet particularly well. We understand this from the very beginning of I.iii, when Lady Capulet tells the Nurse to call Juliet forth to her. Juliet responds to the Nurse, asking who wants to see her. The Nurse informs her that it is her mother and Juliet responds:
Madam, I am here.
What is your will?
Even making allowances for the social status of the Capulets, there is a formality about this procedure which shows that Lady Capulet seldom speaks to her daughter.
In I.iii, Juliet is taciturn and submissive, pledging to do exactly as her parents tell her. Lady Capulet, who barely knows her daughter anyway, can scarcely be blamed for seeing no alteration in her during the few days over which the play takes place. In III.v, when the audience has seen Juliet fall in love, marry, and change completely, Lady Capulet sees the same submissive child and is astonished, then coldly furious, at Juliet's intransigence. After Capulet has behaved with maniacal brutality, Juliet tries a final pathetic appeal to the mother who barely knows her:
O, sweet my mother, cast me not away!
Delay this marriage for a month, a week;
Or, if you do not, make the bridal bed
In that dim monument where Tybalt lies.
This receives the coldest of rebuffs:
Talk not to me, for I'll not speak a word:
Do as thou wilt, for I have done with thee.
When Juliet has apparently changed her mind, Lady Capulet comes tentatively into her chamber in IV.iii to ask if Juliet needs any help preparing for her wedding. Juliet gravely informs her that she is not needed. Even in IV.v, when she believes her daughter is dead, her laments have a hollow, conventional ring, saying only that she has lost the one child she had. Paris, who has barely met Juliet, shows more emotion. Throughout the play, Lady Capulet's relationship with her daughter is distant and authoritarian. She is a stranger to her daughter.