What's Tia's motive??

What's her motive for wanting to hurt Shivaay?? I'm sure you guys probably discussed this but you see I'm new here and have missed quite a bit.
Anyone who can shed a light on to why she's doing what she's doing?? She seems to be wealthy given that she almost blackmailed Shivaay and his family into marriage within one day, I mean if she cldnt help them I don't know if she cld make such promises and get away with it, so that theory didn't work for me.
I don't think there's a bad blood between them considering they were friends almost all their lives, what do you think wld drive her to hurt him??
Maybe the whole family is fraud and don't have a dime in reality. #confused.