Juliet's father doesn't understand that she's crying because of Romeo being banished, not Tybalt's death. So her father tries to make her feel better by changing the date of her wedding to Paris to an earlier date. This makes Juliet even more distressed because she is already married to Romeo, and fights with her parents.
The story of Romeo is quite beautiful however it caused hurt and anger in their parents. But they loved each other enough to die together though the parents may not approve Romeo and Juliet's love was to big in their hearts and souls. No one understood but they understood each other, in the end they thought if they can't be together then their already dead because they weren't together.
