Shakespeare uses the first part of Act Three Scene Five, where Juliet and Romeo are reluctant to leave each other, as a building block to what is going to happen later in the scene. Shakespeare makes the audience feel sad and depressed that Romeo has to leave Juliet as its daybreak. Shakespeare then invents the feeling of suspense as the nurse comes announcing that Juliet's mother is on her way. "Your lady mother is coming to your chamber".
Shakespeare has then changed the audience's feelings from not wanting Romeo to leave, to then wanting Romeo to leave, as he might be killed if he stays any longer. The suspense has still stayed with the audience as the verb "coming" tells that Lady Capulet is not yet there and could come into the room at any moment and find Romeo with Juliet. A director would probably make the actors, who were playing Romeo and Juliet, keep moving around after the Nurse comes in to show the urgency to get Romeo out quickly.
Shakespeare uses Lady Capulet to tell Capulet about Juliet's refusal of the marriage rather than having Juliet tell her father. This could lead us to believe that Juliet is afraid of telling her father about the refusal, and in lines 124-125 it seems that Lady Capulet contradicts herself as she has said "tell him so yourself; and see how he will take it at your hands". This has caused the audience to be surprised yet relieved that Juliet isn't the one to tell her father. If this scene was acted out Lady Capulet would probably tell Capulet just when Juliet is about to, standing in front of her as if