Re: quesion for ladies
Individuals in a relationship are insecure, be it a man or a woman and sharing the attention and loyalty of their spouse with other competing relationships carries with it some fear, whether or not that fear in founded in reality or not.
In the situation described, despite the husband’s avowed loyalty to the first wife and his claims that he is only marrying for sawab and naiki, if he marries the other woman, the husband now has a moral and religious obligation to ensure that she (2nd wife) is happy and cared for and that includes providing her with his companionship. If he denies her his companionship, he is failing in his obligation to the second wife - to phir kahan ki naiki aur kahan ka sawaab?
If he splits his time between both wives, that’s cause for conflict based on the insecurity mentioned above - it doesn’t matter how equitable a man claims to be or in fact is - the fear which is natural makes the situation contentious.
So, since the outcome is sharing the husband’s attention, love and companionship with another woman - no, not many woman would be okay with it or permit their husband to marry the other woman, regardless of his motivation.