In Romeo and Juliet, the feud between the two families has been going on for some time. The Capulets hate the Montagues and vice versa, so when Romeo and Juliet fall in love with each other it presents a major problem. We are told in the prologue of the play of how the story ends and why the two young lovers did what they did.
To households, both alike in dignity,In fair Verona, where we lay our scene,From ancient grudge break to new mutiny,Where civil blood makes civil hands unclean.From forth the fatal loins of these two foes,A pair of star-cross'd lovers take their lives;Whose misadventured piteous overthrowsDo with their death bury their parents' rage,Which, but their children's end, nought could remove,Is now the two hours' traffic of our stage;The which if you with patient ears attend.What here shall miss, our toil shall to mend.
The two families' hatred for each other cost them both the most important things to them. If the families could have just let the anger and hatred go and accepted Romeo and Juliet's relationship, maybe none of this would have happened. Because of the feud, the Friar had to come up with a way that would enable Romeo and Juliet to be together, leading to the very tragic outcome of his decision. If only the families had put their grudge aside, then none of these things would have happened. How tragic that because the families hated each other so much and wouldn't accept the love between their children they ended up losing them instead.