For me it would have to be scene before the new year's party. That was the first time I saw them admitting that they both want to be in a relationship, where Muskan tells Rahul to stay in touch and they can try to maintain a long distance relationship. It showed Muskan's feelings about how bad she wants to be with Rahul. Up until then we had only seen Rahul falling for Muski but that scene brought both of their feelings out. And they ACTUALLY talked like sensible people.
So which RM scene is unforgettable for you?