When Roshni and Jai were dating, Roshni accidently got pregnant. And Jai wanted to marry her, but she didn't want to settle down, Mausi and Dadi and everyone tried to convince her, but she didn't agree and got abortion without telling anyone.
and one day when Jai and Roshni were driving, that's when Roshni gave him the news. Jai couldn't keep his balance, and they got into an accident.......and because of the accident something probably happened to Jai and now he can't be a biological father.
and that's why Jigs probably kicked Roshni out of their life...and probably that's why Mausi and Dadi hates her so much....
let me know what you guys think....