Certainly, the fact that each is, to a certain extent, a level of alienation from their families are evident even before meeting one another. Romeo and Juliet both seem to be a bit distant in embracing the path their families have laid for them. This is widened when they both see one another, perhaps acknowledging the alienation in the infatuation with one another. It adds to the "kindred spirit" element that many like to inject into the dynamics of love. Their predisposition to being separate from their respective families finds an outlet when both become immersed in one another. This raises a very unique level of inquiry. Certainly, they have feelings for one another, but could a primary motivation between them be the fact that they see a way of family isolation in each?
During this period of time, children, especially girls, obeyed their parents without question. Juliet's father becomes very angry and threatens to throw her out on the street when she says she doesn't want to marry Paris. Her mother is completely unsympathetic to Juliet when she begs her for help. When the play opens, Romeo's parents have no idea why he's depressed because Romeo hasn't shared this information with them. There is no doubt in the minds of Romeo and Juliet that their parents would not approve of their marriage. The feud between the two families has been going on for a long time, and the two teenagers would naturally be afraid of their parents' reactions. Even Friar Laurence and Nurse are afraid to confront the parents with the truth, so it's easy to see why Romeo and Juliet don't feel they could go to their parents.
Romeo and Juliet are completely isolated from the support of their families, at least when it comes to their relationship with each other. Neither of them can count on their families to support the relationship in any way.
For example, normally, Romeo would have been able to enlist the support of his father in his attempt to marry Juliet. They were both from good families and their marriage would have been good for both families most likely. But because Juliet is a Capulet, Romeo cannot get his father to go to her father and try to arrange a marriage.
In the play Romeo and Juliet the two lovers are isolated from their families because the knowledge of their affections would cause a bigger blow-up than they already are seeing between the two families. Neither family is tolerable of the other and the idea that one of their children should find a union with one of their enemies children would be a catalyst for even more violence on the families part.
Because of their parents views, their families views, and their families friends views, the couple have become isolated from everyone they grew up trusting with the exception of the nurse and the priest. It is only their youthful hearts that bind them together.