The wedding is cancelled but Romeo has not heard of the plan and thinks that Juliet has died. He couldn't come back due to a plague that spread through the town.
Romeo then hears that Juliet has died so he buys a bottle of poison. He then sees Juliet lying there and he begins to feel upset. As Paris was standing there, he stabs him, drinks the potion, kisses Juliet and dies.
Not long after, Juliet wakes and finds that Romeo had died. She then stabs herself in the chest and dies along with him.