Answer:
The audience knows that Romeo and Juliet's relationship will be affected by the fact that they are from rival families. The Capulets and Montagues have a long-standing feud, and their families are sworn enemies. The audience knows that this feud will make it difficult, if not impossible, for Romeo and Juliet to be together without facing significant challenges and opposition.
Furthermore, the audience is aware that the feud between the Capulets and Montagues is not just a personal conflict between two families, but a larger societal issue that affects the entire city of Verona. This means that Romeo and Juliet's relationship will be subject to the political and social forces that are at play in their world.
In addition, the audience knows that the play is a tragedy, and that Romeo and Juliet's relationship is destined to end in tragedy. The fact that they come from rival families and are caught up in a larger societal conflict is one of the key factors that leads to their tragic fate.