Is it considered a sin or a mistake if the employed wife does not contribute to household expenses and asks her husband to spend on her, knowing that she pays her university installments herself?

A husband must spend on his wife and children in a reasonable manner. The wife is not obligated to share in the expenses unless she agrees to give him a portion of her salary in exchange for his permission for her to work. The husband does not have the right to prevent his wife from disposing of her own money.