Though it was not the raaz it was a lie... Thing omkara hated lies in a relationship his philosophy is that his partner should speak the truth no matter what... This is the thing he expect from his life partner seeing tez decieving jhanvis he had shear hatred to lies... In a relationship...
So they wanted his lead to lie... Ishaana's lies are not justifiable... At all... I pity she chooses that road... Ok fine... She decides people... But the going is... The justification she gave was not complete I don't think anyone get motivated on... Although I wonder why it ended that way Ney...
Daadi said lies is seldom needed in your life to move forward... Sometimes u need to lie so that truth prevails... Gauris lie is doing this... The thing daadi wants to teach omkara is that every lie is not the cause. Of breaking the relation sometimes little lies saves the relation just like this gauri is able to save jhanvis and omkara lo TV of times... And I will strongly recommend that her lie of chulbul will come after Svetlana chapter is end where she is in jail and her move is out... Bceacuse then omkara will be able to understand the benefits of little lies with truth... What his daadi wants to convey...
I hope I have given a justice to the plot what CV wanted to portray ... I know execution is not good... Or something is off... But their motive was this...