The play goes out of its way to suggest that Romeo and Juliet are destined for tragedy. After all, the Chorus tells us in the opening Prologue that the "star-cross'd lovers" will "take their life" and Shakespeare foreshadows the lovers' deaths throughout the play. At the same time, however, the play seems to remind us that Romeo and Juliet decide to commit suicide of their own volition. There are also plenty of players (the meddling Friar and Nurse, Romeo and Juliet's warring parents, etc.) that contribute to the play's tragic events. This may suggest, in the words of W.H. Auden, that, in tragedy, "fate is not an arbitrary person – it is we who are responsible and we bring our fate upon ourselves" (Lectures on Shakespeare, 24).
Romeo and Juliet have no control over their tragic destinies – they are the victims of fate.
In Romeo and Juliet, human beings cause all of the problems in the play and bring about their own fates.