That is bcoz Rrahul and Chandni dont share positive vibes offscreen.
And bcoz none of them are seasoned enough to overcome offscreen wavelength (especially Chandni), it reflects in their performance onscreen.
Yeah I agree this is the reason when Ishaani would get mad at her brother in the beginning it didnβt look out of place because of the non positive vibe off screen. We see that Rrahul shares a good vibe with everyone else off screen which shows on screen especially with Helly and Vishal. Makes a difference these two need become friends or something for us to digest it