According to The Prologue, what ends the rage between two families of Verona?

According to the Prologue of William Shakespeare's "Romeo and Juliet" the feud between the two families will only end with the deaths (or actually the suicides) of the children of the two families who "with their death bury their parents' strife."

At the beginning of the story, the Montagues and the Capulets are sworn enemies.  But Romeo, son of the Montagues, and Juliet, daughter of the Capulets, will soon fall in love.

However, due largely to their families's disapproval of their love, the two end up killing themselves.  It is only with their deaths that the two families promise to end their fighting.