Ak got them married legally and according to ritual as well. So it’s not a deal marriage when they got married. The condition came in later when Abhira was not ready to go with Arman.
Secondly, Ak knew Arman was a good guy when he left lawyering up for Yuvraj after knowing about his crime. He not only went against his family but actively helped Ak to put him behind bars.
Thirdly, when Arman knew Abhira was kidnapped and being forced to marry yuvraj, he left everything to come to save her.
I think these points are enough for Ak to know Abhira will be in good hands after her death and Arman will do everything to protect her from Yuvraj.
Just because of hatred for Ak, don’t make a mockery of a mother who took this extreme step for the well being of her child.
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