How do the Montague and Capulet families contribute to the catastrophe in Romeo and Juliet?

The Montague and Capulet families’ long-running violent feud creates the hostility that drives the tragedy. Romeo and Juliet fall in love despite belonging to opposing families, and the feud contributes to the misunderstandings and deaths that end in catastrophe. The secret marriage, the prince’s authority, and Friar John’s letter matter to the plot, but they are not how the families chiefly contribute.

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