Paris is at Juliet’s tomb because he is heartbroken over her death and wishes to pay his respects. As a nobleman, he had been arranged to marry Juliet, and his love for her was genuine. He believes she has died from grief over Tybalt’s death and is mourning her loss. Paris intends to lay flowers at her tomb, honoring his love and the life that could have been.
Moreover, his presence at the tomb sets up a tragic confrontation with Romeo, who has come to the tomb to see Juliet one last time. This encounter heightens the themes of love and fate that run throughout the play, illustrating how misunderstandings and timing can lead to devastating consequences.