Answer:
The two families – Montagues and Capulets – are to be blamed for their family members' deaths. The quarrel between these two households is basically the main reason why Romeo and Juliet died.
The hatred between the Montagues and the Capulets, the two noble families in Verona, is the linchpin in the story, which causes all the dominoes to keep falling, and finally stops with the deaths of Romeo and Juliet. The ongoing feud is the cause of all the other instances in the play.