From forth the fatal loins of these two foes
A pair of star-crossed lovers take their life (Prologue)

The play’s opening lines tell us that Romeo and Juliet will die, and that their tragic end is fated. “Star-crossed” means “opposed by the stars.” In Shakespeare’s day as in ours, some people believed that the course of your life was determined by the motion and position of the stars. “Take their life” is a pun: it means that the lovers were born from the “fatal loins” of their parents, and it also means that the lovers will kill themselves. Their births and deaths are described in the same short phrase, which again suggests that their deaths were fated from the moment they were born.

I fear too early, for my mind misgives;
Some consequence, yet hanging in the stars,
Shall bitterly begin (1.4)

Before he goes to the masque where he will meet Juliet, Romeo has a feeling that the consequences of his decision to go will be “bitter.” He suspects that this is his fate—“hanging in the stars”—and his use of the word “stars” reminds the audience that he is “star-crossed” (I.i.). Romeo’s fear that he will arrive at the masque “too early” points to an important theme of the play. Almost every event in the play happens too early. Tybalt finds Romeo too early, before the news of Romeo’s marriage has been announced. Juliet’s marriage to Paris is decided too early, before Romeo can return from exile. The lovers die too young.