I think they forwarded the track because the Kartavya vs Pyaar did not fit well for the story especially after the way they established Raghav and Pallavi love story. So they jumped that track and moved ahead to RaghVi vs Mandar track. What is wrong in that. It is quite logical.
Btw how will Raghav know the truth about Mandar ? Pallu has no phone too and is locked in the room ?