Is the wife entitled to maintenance and to file a lawsuit while refusing to return to the marital home and abandoning the children due to the husband's marriage to another, and is she considered a rebellious wife (nashiz)?

A wife is not permitted to leave her husband's home without his permission, unless there is a legitimate Sharia-compliant reason. If she leaves merely because he married another woman, she is considered rebellious (nashiz), and she loses her right to overnight stays and financial support. Polygyny is permissible for those who are able to practice it; it is a good and recommended act. A wife who becomes angry and goes to her family's home because her husband married another woman forfeits her right to equal division (of time spent with him). We advise striving for reconciliation between spouses, especially if they have children, as divorce has negative consequences for them. Divorce should only be resorted to if its benefits outweigh its harms.