Sneh, Rishi and Dev are from the same college. Rishi was a poor boy, he loved Sneha but never told her due to his status. Sneha loved Dev and Dev loved Sneha's money. Mr Chaubey fixed Sneha's marriage somewhere else, so she ran away to Dev. When Dev learned this he cooked up a plan to get money from Chaubeys by using Sneha, Rishi somehow got to know all these and stopped Dev, when his plans failed he ditched Sneha. By this time everyone got to know Sneha ran away so she couldn't go back home, she tried to comit sewside and Rishi saves her, he marries her and everyone gets to know about the wedding. Chaubeys think Sneha ran away with Rishi and starts to hate them, since Chaubeys are influencial and powerful people everyone goes against the couple and they had to leave Banaras. They go to Mumbai and Rishi works hard and becomes successful, seeing his love and care Sneha slowly fell in love with Rishi.(this is why Sneha don't know when she fell in love)
Well since our Sasura is on a mission to find out the past story, we will get to know the real story soon...