Prologue: Lines 4-6
This is the first instance that fate and the stars are aligned to reveal Romeo and Juliet’s destiny. These lines suggest that lover’s fate was decided before the two ever came into existence. The combination of “fatal loins” and “star crossed” gives the audience a sense that the destiny of these two lovers is beyond their mortal control. In fact the responsibility is placed is placed on the situational aspects that their families are in because the very loins that belong to the Capulets and Montagues are in fact lethal to any who are conceived by these parties.

Act 1 Scene 4: Lines 106-114
This section is Romeo’s premonition concerning his up and coming death. Urge to go to the Capulet ball by Mercutio and Benvolio, Romeo takes a minute to contemplate a feeling that he should steer clear of these circumstances. He discusses “consequences” hanging in the stars that lead him to believe that there is some great tragedy awaiting him in the process of his journey. In truth, this is the beginning of the chain events that will lead Romeo and Juliet to their unexpected deaths. Alongside, Romeo also speaks to unknown deities by commentating on the “steerage of my course”. This suggests that Romeo believes that he is in the hands of unknown origin and that this power steers him to where he is meant to go; in short this is called fate.

Act 3 Scene 5: Lines 12-13
Juliet explains images of darkness and light, which are based around the discussion of a meteor that is to light Romeo’s journey to Mantua. These circumstances remind the audience of the “star crossed” lovers symbolism in the opening prologue. The fact that Juliet refers to the meteor as a notion that the sun is not rising, but in fact it is a passing light that takes Romeo from her. Ironically, the meteor can also be referred to as fate because this is the final time that the audience sees Romeo and Juliet alive together and the torch is like a bell that calls out death for the star crossed lovers.

The best thing to do is to download the etext from here:
http://www.enotes.com/romeo-text/

and then do a search for "stars" and "fate" you should come up with many more.