Is what happened with the first wife considered an injustice to her, and is the husband obligated to marital intimacy during the period of separation, and are there specific conditions to avoid injustice to the wife, and does separation differ from divorce in ruling?

Among the wife's rights upon her husband are intimate relations conducted with kindness and fairness among co-wives. It is permissible to reconcile over the waiving of the right to spend the night. Previous problems should not prevent the husband from having intimate relations with his wife and ensuring her chastity. He must be patient, overlook shortcomings, and focus on the good aspects of her character, for Allah Almighty says: "And live with them in kindness. For if you dislike them – perhaps you dislike a thing and Allah makes therein much good." And he should not despise her, for the Prophet (PBUH) said: "A believing man should not hate a believing woman. If he dislikes one of her characteristics, he will be pleased with another."

A wife's separation from her husband in residence with his consent, without divorce, does not nullify her due rights unless it is due to her disobedience (nushuz), in which case her right to spend the night and her maintenance are forfeited. She may waive her right to spend the night with her consent, and the husband is absolved of sin. She may claim her right whenever she wishes. He must provide for her and his children with kindness. This woman remains a wife as long as no divorce has occurred, and she has the rights of a wife and owes the duties of a wife.