The Sunshine to my Shadow Lover

When Surya met Sanjana, a well-stitched love story was on the books. Even in between petty fights and arguments, Surya knew that he had to overcome his emotions into accepting that he cannot hurt the love of his life in anyway. Struggling with the past and the present, the happy couple’s entire future has been put into jeopardy when Chaya comes back into the picture. Who is she? What does she want? Where does Chaya figure herself to be in the story of Sanjana and Chaya?
It all boils down to one favor Sanjana asks her to do for her. A favor that would make or break her entire future with her fiancé. What was the favor? Does this lead to a happy ending?