In the prologue, Romeo and Juliet are described as “star-crossed lovers.” This implies, at least partially, that they are fated for each other. Yet they were born into feuding families. Fate does seem to throw them at each other, because Romeo’s friends brought him to the party, and he was on the rebound from Rosaline. Had Rosaline not just dumped Romeo, he would have been at the party with her and would not have thought twice about Juliet. Thus Fate played with both of them.
Romeo and Juliet fell in love instantly. This is because Fate designed it thus.
O, she doth teach the torches to burn bright!
It seems she hangs upon the cheek of night
Like a rich jewel in an Ethiop's ear—
Beauty too rich for use, for earth too dear! (Act 1, Scene 5)
If Mercutio and Benvolio had not been sitting around when Tybalt arrived, they would not have gotten into the fight that eventually led to Tybalt’s death to avenge Romeo, which got Romeo banished.
If Romeo had not missed the letter telling him about the potion plan, he would not have killed himself when he saw Juliet. If Juliet had awakened only moments earlier, he would have known she was alive and they both would have lived.