He loves his dad alot and trusts him so of course he wont beleive in words...he needs prove...like gaurav told him he knows about his parents problems..but what problems...he wasnt there he does not know...why didnt gaurav tell him of how his parents separated for a while and everything he knows...why didnt dev tell him of his dad's affairs and his physical abuse on her...why didnt bauji tell him everything he knows and back up dev...why didnt priya tell him about how brama tried to rape her...if he doesnt beleive anything else he would beleive this one...they dont even have to bring uttara's name but tell everything else...why dont they bring RD to tell him everything she knows...after all that he would beleive them...but just saying your dad is a bad person he wont understand...