Naksh was angry on Niara for hiding injury from Karthik?

She got trapped by Suwrana and her emotional blackmail/ fake suicide drama and did not tell Karthik that she never left but fell down from Terrace.

I think Naksh wanted her not to get into Suwrana;s clever trap and to let Karthik know what happened that day. But she chose Suwrana and succumbed to her psychosis.