In Act II, scene II, "The Balcony Scene", Juliet is on the balcony in her room, daydreaming and talking about Romeo. As she is talking about him, Romeo overhears her. They begin talking of their love for each other. Juliet states the danger that they are both in for loving a member of their family's rival family. Romeo says that he does not care, though, and that his "...life were better ended by their hate, Than death prorogued, wanting of thy love."
To begin, Act II, scene II, is important in the play because it sets up their proposal for marriage. Both Romeo and Juliet find out that the person that they love is in love with them, too. This confirmation gives them the idea of marriage. Their love is so strong that their wedding is planned for the very next day. The plot begins to become complicated when they realize the danger in them being in love and especially in them getting married.
To continue, in the beginning of this scene Juliet is feeling lonely, thinking about Romeo. When Romeo arrives beneath the balcony she is on, she becomes excited that she is able to talk him, the one that she had been daydreaming about. Since Romeo already overheard her talking about him, she confesses to him how strongly she feels for him. At the end of this scene, she proposed marriage to him, and tells Romeo that she will send for him at 9 the next morning so they can go and get married.
Finally, without this scene, Romeo and Juliet would not have planned to be married the next day. Romeo might have still gone and fought Tybalt, so Mercutio and Tybalt both could have died still. After Romeo killed Tybalt, I don't think that...