One thing I've noticed about Riddhu's character
Whenever she does a mistake and is cornered by vansh she behaves very softly and meekly towards him. On the other hand when she realises he didn't get proof against her she speaks up boldly and insults him. Most of the time she is rude to him and even calls him shaitaan but when she is caught in an act she behaves like she is the sweetest angel.
The change in her character is so obvious I don't doubt that vansh has noticed it. He is smart and observes when she starts getting stressed and sweats. So he would have realised the pattern of her behaviour also.
It's out of respect for his wife that he doesn't shout at her and keeps on repeating for her to stay in her limit. And Riddhima as usual doesn't pay heed to his words and keeps on playing with fire.