Is a woman sinful if she does not return to her husband who has divorced her twice, fearing that he will divorce her a third time, given that they have three children?

If the iddah (waiting period) of the second divorce has expired, the wife becomes irrevocably divorced with a minor separation (baynunah sughra). She is not permissible for her husband except with a new contract and a new mahr (dowry). She is not obligated to return to him, and she does not sin by not agreeing. She should consider her own best interest and the best interest of her children.

However, if the iddah has not expired, she must immediately return to the marital home and stay there. It is not permissible for her to leave except for a need during the day, or for a necessity at night to stay outside. Otherwise, she sins and is considered disobedient (nashiz) if she leaves without her husband's permission, as Allah Almighty says: "You shall not expel them from their homes, nor shall they [themselves] leave, except if they commit a clear immorality." (Quran 65:1)