After Goddess Sita was abducted by the demon king Ravana, Goddess Sati transmuted herself to Goddess Sita to examine whether Lord Rama was actually the incarnation of God.
As soon as she approached Lord Rama, he bowed down before her in reverence.
Seeing this, Goddess Sati was so embarrassed that she immediately returned to Kailash.
Upon reaching Kailash, Lord Shiva asked her how did she test Lord Rama to which she didn’t reply. He then used his spiritual powers and got to know that his wife had transmuted herself into Goddess Sita to test Lord Rama.
On knowing this, Lord Shiva grew angry and stopped interacting with his wife. He went into deep meditation under a tree for 87,000 long years.
Goddess Sati repented on her shameful act .She even begged Lord Brahma to meet death as it was the only way to purify her from such a sin.
One day, Prajapati Daksha had organised a grand ceremony for Lord Vishnu.
He called upon all the gods and goddesses except Lord Shiva as he did not revere him as a God.
Since Goddess Sati was the daughter of Prajapati Daksha, she thought that her father would have forgotten to call her and her husband in the grand ceremony.
Smitten by curiousness, she went to her father’s palace only to see that he had deliberately not called Shiva and Sati as there was no seat placed for the couple.
Seeing her husband being insulted in front of so many people, she jumped into the fire altar and self immolated herself.
Thus Goddess Sati sacrificed her life in order to save the honour of her husband.
Later, she was reborn as Goddess Parvati and married Lord Shiva.