The blame isnt for Ruhi falling asleep on him but for the liberties he gives her in general and the way he treats her despite knowing her intentions and her delusions. He doesn't behave like a guy who is trying to keep distance or getting over a breakup at all. And somewhere all her shamelessness is fueled by that response from him. Ruhi would not have the guts to behave the way she does if he had put her in place firmly. She can afford to do everything she does because of his reactions giving her the confidence to continue her lusty behavior.
If Armaan did the needful firmly without mixed signals and melting at her manipulations ans Ruhi did all this, only she'd be blamed by all unanimously and everyone would sympathize with him and term her behavior as harassment and him as victim. But here thats not the case.
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