What is the ruling on marrying someone who takes his family to public places where they smoke shisha (only their faces unveiled), and his sister sits with men, and her husband does not object?

If this is his situation, then it is better to leave his marriage, according to the words of the Prophet, peace and blessings be upon him: "If someone whose religion and character you approve comes to you seeking marriage, then marry him. If you do not do so, there will be tribulation on earth and widespread corruption." However, if you are unable to convince your father and sister to reject him, then convince your sister to adhere to virtuous morals, to the impermissibility of mixing with strangers, and to the impermissibility of her looking at them and their looking at her, and that it is not permissible for her to obey her husband in disobeying her Creator.