Mihir most probably then calls ishita to for one on one meeting to explain why he can't go against Raman
He may reveal that he is Shagun brother
Then when they are talking they may spot simmi
They then might have spent the entire day chasing her
Then ishita might have discovered something shocking about simmi
Simmi may ask ishita not to tell anything to anyone
And that why ishita to hide the truth may behave oddly strangely and coldly with Raman