Suspense and tension are interrelated concepts which work together to maintain an audience's attention. Suspense refers to the audience's expectation of a certain outcome. The audience, because of its empathy and concern for a character or characters, is what defines the tension in a drama.
In Romeo and Juliet, Shakespeare has involved the audience in the circumstances of the two doomed titular characters and has created a situation in which the audience, although it already knows what will happen to the young couple, is keen to know how the exact details of their deaths.
The scene opens with Paris, Juliet's would-be groom, entering the graveyard at night. He bears flowers and heads toward the Capulets' tomb where Juliet, believed to be dead, is interred. The darkness and audience's knowledge that Romeo is heading in the same direction add to the suspense.
The veil of darkness creates a dangerous and portentous atmosphere. Furthermore, there is bound to be a confrontation between the two men, as Romeo was banished at the risk of death but was now, in spite of this, in Verona.
Paris's page whistled to warn him of approaching danger, increases the tension, since the audience is concerned about Romeo's well-being and does not want him to come to any harm. His arrival heightens the tension. The audience knows a confrontation is unavoidable, and there is suspense about how events will unfold.
Once Romeo opens the tomb, Paris recognizes him and steps forward to confront him. He cries out to Romeo and tells him to stop and surrender. Romeo admonishes him and tells Paris he must leave. The tension increases even more because the audience knows Romeo is there to commit suicide and will be keen to know whether Paris will prevent him from doing so or will kill the young Montague himself. Paris refuses to back down, and a fight ensues. Paris dies.
When Romeo enters the tomb and sees the supposedly dead Juliet, he says a number of passionate rhetorical questions and metaphors before he decides to drink the poison he brought with him. The audience would by now be completely engrossed and would hope there is rescue for the boy. Friar Laurence's arrival adds to the palpable tension, for he should be able to rescue the situation or, at least, save Juliet.
It is not to be. The friar is appalled when he sees the dead bodies of Romeo and Paris inside the tomb. Juliet wakes, and the friar pleads with her to leave with him. The suspense and tension in this particular situation is at a breaking point. The audience hopes Juliet will follow the friar's advice, but she stubbornly refuses. Shakespeare uses her rhetoric to delay her final act, further increasing the tension. Juliet grabs Romeo's empty potion bottle but finds it empty. She takes her dead love's dagger and kills herself.