Why are romeo and families rivals?

Romeo and Juliet's families, the Montagues and Capulets, are feuding for reasons that are never explicitly stated in the play. It is referred to as an "ancient grudge," suggesting a long-standing rivalry between the two families that has been passed down through generations. This feud is intensified by the violence that has occurred between the two families in the past.

The rivalry is further fueled by the mutual hatred and mistrust that exists between the Montagues and Capulets. Both families are quick to anger and eager to fight, and they are constantly looking for ways to one-up each other. This rivalry is a major source of conflict in the play and leads to the tragic deaths of Romeo and Juliet.