Did Shakespeare create a believable love in Romeo and Juliet?

I believe he did, yes, for a few reasons.  First, Romeo and Juliet are both so young; we know Juliet is thirteen, and though we do not know Romeo's exact age, most readers assume that he is also a teenager due to his behavior.  Teenagers have a tendency to feel things really, incredibly deeply, and so Shakespeare's representation of their love as intensely passionate and overwhelming feels very true to life.  Teenagers also have a tendency to lack perspective needed to see that the way they feel today isn't necessarily the way they will feel next week or next year, and everything often feels very immediate and urgent. 

Further, Romeo and Juliet believe that their parents would oppose their match; they talk a lot about the danger Romeo would be in, especially, if he were found in Juliet's garden or bedroom.  It is developmentally appropriate for teenagers to rebel against their parents and to do things to which they believe their parents would object.  Therefore, Romeo and Juliet's intense feelings and their drive to pursue those feelings at all costs, despite anticipating their parents' disapproval, seems very realistic and believable.