I think it's gonna be trust issues in their love story. Given Reyansh's background he can never trust any women, cause of his mum.
There are multiple instances where we see it.His friend in the CCTV scene says R always reacts and jumps to wrong conclusion. Even on the wedding day they have similar conversation.
R keeps on asking A again and again about tellu and her single status. He just cannot accept that A is saying the truth. In the latest promo too he again asks A and Vikram that you sure that something is not going on between you both, even though V is his best friend and now married.
I agree. He also thinks she loves him thus the possessiveness and obsession