The reason is not the lie it is the fact that pratigya told krishna she is leaving the house. If she had left with parents and no interference from ss it would have been Takur insult. This way he has taken that away from pratigya and insulted her instead. Krishna knows that pratigya would not have left especially as he threaten her try and go.
ss is what i called old school my great grandfather jimana a womens place is under the shoe. He has not been shown anything else but that so for him to see this women answering back it is a hugh shock.