Not sure about who it can be. But more humiliation for Preeta is on the way. May be, not all would blame Preeta this time. I think there is going to be a paparazzi article about Karan Preeta sleeping together and that's why Preeta will have to stay at Lutra house.
Since Mahira has again started the blame game, Karan might again hate preeta but will be torturing her more by allowing her to stay at LH.
But by staying there Preeta might help Mahesh recover too which later will prove her innocence too.
