This scene sheds light on why Juliet is so distanced from her mother. When Juliet expresses her oppositon to marrying Paris (and thus defying her parents wishes for a monetarily beneficial match) Lady Capulet fumes: "I would the fool were married to her grave!” Juliets mother will offer neither intervention nor consolation for her daughter.
This scene also serves to futher isolate Juliet from any adult who might give her wise guidance. Even her beloved nurse abandons her; she too advocates marriage to Paris. Juliet feels she has nowhere else to turn other than Friar Lawrence, whose occult-like schemes should be suspect to anyone with sense.
The end of the act finds Juliet and Romeo alone in their immature ability to reason. The result is the inevitable tragedy.