Is it permissible for a wife to stay with her sexually incapacitated husband, enduring the hardship of loneliness on her own, or should she leave her son, and is it permissible for her to love him as her brother?

If the husband is righteous and there have been children born from him previously, it is more fitting for the wife to be patient and seek treatment for his illness with him, while increasing supplication and earnest prayer to Allah for healing, for every disease has a cure. Both spouses should fear Allah and frequently supplicate during times when answers are likely.