This is a massive area of debate, as Shakespeare presents Romeo and Juliet as being "starr cross'd" from the very introduction of the play. Fate and destiny is something that obstructs their happiness, seemingly at every turn, and reference is made to it by Romeo and Juliet at various stages of their travails. Note, for example, Romeo's defiance when he hears news of Juliet's supposed death: "I defy you stars!" Likewise, note Juliet's speech to "Fortune" in Act III scene 5. It seems improbably that fate, destiny or fortune (call it what you will) would plot to prevent these lovers having a happy ending, especially as so much good could come from it, as Friar Lawrence is well aware. However, again and again, in the seemingly accidental loss or mis-delivery of the letter to Romeo in his exile for example, and the way that the lovers just miss meeting each other, fate seems to rule and to have pre-determined the tragic end to this most romantic of stories.