Is a divorced woman marrying a married man considered a sin or an injustice to his wife, and does the Hadith "There should be no harm or reciprocating harm" apply to it, especially with the conviction of the man's piety and justice?

Allah has permitted a man to marry more than one woman—up to four wives—on the condition of just treatment among them. There is no sin upon a woman for marrying a married man, nor is there any disfavor in it. This marriage is not considered a forbidden harm according to Islamic law if the husband adheres to justice. Even if a specific harm occurs to the first wife, it is tolerated to avert a general harm, which is the abundance of women and scarcity of men, and the resulting spinsterhood and forbidden relationships. As for Istikhara (definition) (seeking guidance from Allah), its meaning is to ask Allah to choose what is best for the servant in their religious and worldly affairs. It cannot be definitively asserted that Allah has chosen a specific matter merely because of a dream or a feeling of comfort, as these are only signs that can be taken into consideration. As for customs that prohibit polygyny, they are invalid and not to be considered, as they contradict Islamic law.