One of the most popular legends associated with Uma-Parvati & Shiva is their love affair in Uma's previous birth when she was Sati, daughter of Daksha, a divine King. This story is mentioned in Devi Bhagavat Puranas & Epics like Ramayana & also in great poet Kalidasa's Kumarsambhavam. 

Sati since childhood was attracted to forest-dweller Shiva, she was growing up with his valorous stories & decided to marry Shiva. Princess daughter marrying to a forest-dweller ascetic Shiva was demeaning for King's majesty & thus King Daksha opposed her. But adamant Sati gave up her luxury of palace to be with ascetic Shiva & went to forest against all odds. 

One day Daksha arranged grand Yajna & invited all the deities except Shiva but yet Sati decided to attend Father's Yajna. When she arrived at ceremony, Daksha humiliated her & insulted her husband Shiva. Humiliated Sati couldn't bear her beloved husband's insult & committed suicide in sacrificial fire. When Shiva came to know about this he wrecked havoc in Daksha's kingdom with his Tandava & the world suffered separation of Sati & Shiva. 

Rabindranath Tagore exemplified this event as-

"The evil spirit is exultant and paradise is lost when Sati, the spirit of (Reality), is disunited from Siva, the Spirit of Goodness. The Real and the Good must meet in wedlock to save all that is true and beautiful."

Separated from beloved wife, Shiva was distressed for many days. Later in story it is said that Sati who couldn't bear her husband's suffering decided to reborn as Uma-Parvati to unite with Shiva. 

This benevolent & erotic sculpture of Uma-Maheshwara is dated back to 10th century from central India, 2 sons Ganesha & Kumara can be seen on top most right & left corner of sculpture. This sculpture is placed in National Museum Delhi.