Why did Juliet stab herself?

Directions: Read the following passage and answer the given question.

The messenger, however, does not reach Romeo and, instead, Romeo learns of Juliet's apparent death from his servant, Balthasar. Heartbroken, Romeo buys poison from an apothecary and goes to the Capulet crypt. He encounters Paris who has come to mourn Juliet privately. Believing Romeo to be a vandal, Paris confronts him and, in the ensuing battle, Romeo kills Paris. Still believing Juliet to be dead, he drinks the poison. Juliet then awakens and, finding Romeo dead, stabs herself with his dagger. The feuding families and the Prince meet at the tomb to find all three dead. Friar Laurence recounts the story of the two star-cross'd lovers. The families are reconciled by their children's deaths and agree to end their violent feud.