This is the story of marriage of Shiva and Shakti for the second time on the day before new moon in the month of Falgun which is celebrated as Maha Shivaratri. Once Lord Shiva and his wife Sati or Shakti were passing by a forest where they met Lord Rama who was in search of his wife Sita being kidnapped by Ravana- the king of Lanka. Shiva bowed before Rama to pay reverence upon which Shakti was surprised and asked why he paid reverence to a mere mortal. Shiva then told her that Rama was the incarnation of Lord Vishnu. To check this, Sati took form of Sita and presented herself before Rama who at once recognized her. However, Lord Shiva, who looked at Sita as his mother could not accept the fact that his wife Shakti became Sita. He got detached from Sati as his wife.
Once, King Daksha, father of Sati organized a Yagna but did not invite Shiva due to differences with him. Sati still went to the yagna despite the wishes of her husband but her father ignored her presence and insulted Shiva by not offering prasad for him. Sita felt humiliated and jumped into the yajna fire and immolated herself.
When the news of Sati’s immolation was heard by Shiva, he got furious and started performing Rudra Tandav dance. He destroyed the kingdom of Daksha. Everyone prayed Vishnu as Shiva’s tandava could destroy the whole Universe. To calm Shiva down, Vishnu severed the body of Sati into twelve pieces and threw them on earth so that Shiva could not destroy earth. Wherever the 12 pieces fell down there emerged a Shakti Peeth (12 Shakti Peethas are the great pilgrimage destinations for the devotees of Shakti)
Lord Shiva undertook penance and went to Himalayas to perform meditation. Sati took rebirth as Parvati in the family of God Himalaya. In order to bring back Shiva from ascetism, Parvati took penance to break his meditation. Finding it very hard to do this, she took help of Kamadeva- the God of Love and Passion. When Lord Shiva’s meditation broke due to the arrow of passion shot at him by Kamdeva, Shiva got furious and reduced Kamdeva to ashes. When Rati, wife of Kamadeva, pleaded then only Shiva revived Kamdeva.
Realizing her fault, Parvati undertook severe penance to win over Lord Shiva. Through her devotion, she was able to bring back Lord Shiva into the worldly matters and they got married again. Their marriage took place on the day before Amavasya (new moon) in the month of Phalgun. This day is, since then, celebrated as Mahashivratri every year.
Variations of this Mahashivaratri Legend
Another version of this Mahashivaratri legend of marriage of Shiva and Shakti states that Goddess Parvati performed tapasya (penance) and prayers on the auspicious moonless night of Shivaratri to ward off evils that may befall her husband- Lord Shiva. Since then, women began the tradition of praying for the well being of their husbands on Shivaratri day. Unmarried women pray for a husband like Shiva, who is also considered to be the ideal husband.