I wrote already last week that everything is RK's plan to give MB self respect back and some kind of satisfaction.He is intelligent and he knows that they must be same ( chance for new relationship without dirty games).Who gave him idea ? Deepali, as she said that she and RK are the same. He thinks after ''her revenge'' will be everything ok and they can start a new love story. What is important for RK ? That MB loves him,only him ( deep and true like before ) . And Sultan has no chance.
What RK doesn't see is that this time MB's ego is bigger and bigger ( and her love weaker ?). He will trust that she loves him. That will be his first mistake.