Yes, the families' feud is the driving force behind Romeo and Juliet's decision.
Explanation:
As explained in the play, the Montagues and Capulets have a well-established hatred towards each other. When Romeo and Juliet met, they did not know that they were each in the rival family. Despite the families' rivalry Romeo and Juliet fall in love. In Act 2 - Scene 2, Romeo and Juliet discuss running away, this way they can be together. Their families have banned them from seeing each other so this, in their minds, is the only way to be together.
All of this said, you can clearly see that the families' feud is the driving force behind Romeo and Juliet's decision.
