Are the actions of the husband's sister correct in terms of her frequent communication with her brother, seeking his opinion on everything, and sharing private details with him, and is a Muslim man's responsibility towards his married sister greater than his responsibility towards his wife?

The wise wife must be keen to develop and strengthen her husband's relationships with his family, and not think that his attention to them will make him neglectful of her and their children. The wife should gently advise her husband if he falls short in his duties towards his home and children, without criticizing his love for his family. The husband is also advised to consider his wife's feelings and increase his attention to her and their children.