I think he has been told a lie that he believes is the truth. Ramu too agreed to this, he is at fault too.
Ranisa is manipulating Veer so that even when she does something to Ramu, he won't blame her.
May be the pole that Veer was holding in the fire scene symbolizes the accident truth, or what Veer knows. And he will reveal it only when Rani become in danger.
Even after he reassured Ranisa, she was still afraid that he might do something. Can't believe she is actually willing to kill Ramu. This accident mystery seems very deep.
Rani Sa knows Veer never keeps promises. So she is scared he will break this promise too. She knows when it comes to Rani he can be changed a the nth moment.