@Aditi Shruthi here. You have done a beautiful analysis of Dev and agree to you. Yes Dev will manipulate things so that he gets what he wants.
But we need to know he is a businessman. If a business man is not shrewd cannot do successful deals then no use calling him a business man.
Ishwari will also have to bow to Dev. He will make her do what he wants his own way. Look at Ishwari now. How she eats as per her diet. đđ. But with Ishwari he cant do it alone. He needs Sona to ensure he have his way. See its Sona's professional commitment that has made her come back atleast 2 or 3 times even when she had fight with Dev.
And even when Ishwari doesn't like Sona, her love for Dev will bring Sona to Dev when he needs her the most, when the world is against him. Only then Ishwari will understand why her son had choosen Sona. What he had seen in her, which she was unable to see.
There was a dialogue Ishwari says. She doesn't want a girl who is rose, but who is tulsi as her bahu. Tulsi is that plant which is never kept inside the house, but without it pooja of Krishna is incomplete. Tulsimala is Krishna's favourite haar and in every Krishna pooja tulsimala is used. Tulsi wanted only Krishna, not his wealth or power.
Sona is that tulsi who will love Dev for what he is not for his wealth or power.