Ranvir becomes Sushir's friends. Sushir will share about Ragini with him. If Ragini tells Sushir about Anmol then possibly it will be via him Ranvir finds out thetruth.
2nd possibility is that if Sushir-Ragini marriage is fixed, Mamaji will inform Sadna about it. Vasu will poison Ranvir mind about Ragini-Sadna regarding this once again.
There is another possibility that Sushir becomes Ragini's best friend & tries to clear the misunderstanding b/w RagVir.