What is wrong with Purva?

Hey guys

I dont understand whats wrong with Purva. Why does she want Smiriti to live in this House. Everyone is always humiliating her. And Mihir doesnt love her anymore so Purva cant force Mihir to love Smiriti.Why does she want Smiriti to suffer more by living in that house. If she really cares and loves her sister she should just convince everyone to give Prem to Smiriti who has full rights on him and go somewhere else and live happily. Or if Purva really wants her sister to be with Mihir and stay in her house then why doesnt Purva just leave and let Smiriti have Prem and Mihir. She cant make Mihir fall in love with Smiriti when she is there too.

Purva is the worst sister ever, first she marries her sisters husband even when her sister is alive and now she is making her sister suffer even more by living in that house where no one wants her.

I dont even want to comment on Mihir because his character is just disgusting and there is no justification for him falling in love with Purva and falling out of love with Smiriti.