They Did it to Themselves
The fall of Romeo and Juliet is a culmination of many factors. A controlling father, an ongoing feud and a gullible friar all contribute to this catastrophe, but, for the most part, it was Romeo and Juliet themselves that lent a hand to their own doom. The two lovers were fated to meet and die, but this never could've happened without their help. Had they been patient and rational, perhaps the situation would've worked itself out, but what can one expect from a couple of thirteen year olds who insist that they are in love?
The first instance of Romeo's immaturity occurs when he first encounters the lovely Juliet. He know that the party is hosted by the Capulets, and yet he still chooses to attend anyway. As a teenager, he loves to party and is sure that there will be pretty girls there in which to flirt with.
Instead of being rational and realizing that this party was a bad idea for a Montague, he and his friends enter without fear.
Once the party is over, Romeo hears Juliet on her balcony talking of how she loves Romeo and together they speak of their impending marriage. What? It seems that they are obsessed, not in love. How could they love each other when in fact they have just met hours earlier? They are children who have crushes and plenty of melodrama to enhance it.
Romeo demonstrates his immaturity again when he slays the Capulet, Tybalt. Being an idealist, he does not think about the consequences of his actions. He knows that Tybalt is Juliet's cousin, and that injuring him would wreck any chance of them getting together legitimately, yet he does it anyway. Instead of pausing a moment and thinking about the situation...