Ravan wanted to marry Sita and thought that if he could convince Sita of Rama's death, she might agree to marry him.
He went to a rakshasi called Vidyut Jibva, and asked her to create a head similar to that of Rama's. Showing Sita the head of Rama, Ravana said, "Look, you foolish woman, my demons have killed Rama. You have to marry me now."
Saying these words, Ravana went back laughing to his palace. Sita believed Ravana and heart broke. She wept for Rama , but Trijata consoled her saying that it was just a trick by Ravana. She said she had seen a dream that Rama was approaching Lanka. Sita was overjoyed to hear her words.