Lady Capulet's next proclamation comes as something as a surprise to Juliet, but not to the audience. We have been given the perception that the Nurse is the person who most closely resembles Juliet's "mother", and that Lady Capulet was not very involved with her upbringing, so when she asks to 'speak with her', we immediately suspect that an ulterior motive may be present. Our suspicions are confirmed when Lady Capulet tells Juliet that her father, Lord Capulet, has arranged for her to be married to Paris. She is caught unawares and rejects it completely. Her father is angered by what he interprets as insubordination of sorts, and, enraged, issues an ultimatum; she is to be married by next Thursday, or he will disown her.
Shakespeare manipulates the audience wonderfully with the dialogue leading up to this scene, as well as building a picture of happiness - unbeknownst to us, the scene with Romeo & Juliet at the window is the last time they will see each other alive, and Romeo's departure from Juliet's company marks the beginning of the downward spiral of events leading to the climax of the play. The language used at the culmination of the balcony scene is perhaps, in retrospect, the most striking use of dramatic irony in the play.
Juliet: O God, I have an ill-divining soul! Methinks I see thee now, thou art so low, as one dead in the bottom of a tomb. Either my eyesight fails, our thou look'st pale.
Romeo: And trust me, love, in my eye so do you: dry sorrow drinks our blood. Adieu, adieu!
The scene where Juliet's mother arrives is perhaps the most intriguing. She surprises Juliet by bringing up the subject of marriage, at a time when she has just married Romeo. She unequivocally refuses both because of her feelings towards Romeo, and also her religion - marrying Paris would amount to polygamy, a practice which is strictly forbidden by Juliet's religion. She reacts angrily to the suggestion, and her reasons for doing so are spoken in double meaning, whereby each statement could either be referring to her love of Romeo, or the hatred that her mother believes she is directing toward him as a result of his killing Tybalt. Her father is incensed - he cannot understand why she has, in his view, insulted her by rejecting what he views as a perfect union. Juliet's language constantly veers dangerously close to revealing her love for Romeo, and is even literally expressed at one point - "... I will not marry yet, and when I do, I swear it shall be Romeo, whom you know I hate, rather than Paris.". Her mother fails to grasp the true intention of her words, and tells her to inform her father of her decision. This scene is full of tension, mainly because the audience is on tenterhooks, waiting to see if she will let her feelings overcome her common sense and let slip her secret. In the context of this scene, I am sure it would not be uncommon for the audience to gasp in response to Juliet's proclamation - almost as if they were watching a pantomime, rather than a Shakespearian tragedy.
An observation I made whilst reading through the play is that this scene, in which Romeo bids Juliet farewell, and Juliet prophesises their deaths, is entitled "Act 3, Scene 5", while the final scene in the play, in which Romeo bids Juliet farewell forever and commits suicide, along with Juliet soon after, is entitled "Act 5, Scene 3". While it is possible that Shakespeare did this deliberately, these scenes are strikingly similar. Both have been built up to by mixing anticipation with expectation, and both have very obvious climaxes - Act 3 Scene 5's climax is Juliet's wholeheartedly disobeying the wishes of her parents, and Act 5 Scene 3 culminates in the death of the play's main characters. The similarities in both are evident both in dialogue and setting - Romeo's almost poetic soliloquies about Juliet's beauty and life being finite - are present in both scenes, as is the actual plot of both - Juliet's decision to let Romeo leave in Act 3 Scene 5 proves to be a fateful one, as he kills Tybalt out of revenge for Mercutio's death, and also in Act 5 Scene 3, as her decision to go along with Friar Lawrence's plan to fake her death.
Shakespeare's use of tension in Act 3 Scene 5 is used in perfect amounts - slowly at first when Romeo doesn't leave Juliet's room immediately, and powerfully during Juliet's anger towards her arranged marriage to Paris. To achieve this, Shakespeare masterfully balanced both dialogue and plot to subconsciously build the audience up to the point where she is in effect abandoned by her family, as we know she cannot carry out her father's ultimatum with regards to marrying Paris. Shakespeare manages to shift our perspective of the play so it feels as if we are seeing the events unfold through Juliet's eyes.