What is the ruling regarding a husband divorcing his wife because he prefers her female cousin over her, and are the feelings of the female cousin towards him considered a betrayal of his wife, and what is the ruling regarding her parents and relatives refusing to marry her to him for this reason?

Divorce is permissible, especially when there is a need for it, and a man does not sin if he divorces his wife because she does not agree to him marrying another. Marrying more than one woman is permissible in Islamic law, provided one is able to be just. Feelings of love before marriage have their controls, and your marriage to the man – if it happens – does not involve betrayal of his wife. If the suitor is religious and of good character, then the parents do not have the right to refuse him. You should try to convince them, and if they are not convinced, you may refer the matter to the judiciary for the judge to marry you if the guardian's obstruction is proven. Scientific and financial differences do not prevent marriage to a suitable person, and what is considered in suitability is religious commitment. Referring to the authority (the judge) in cases of guardian obstruction is better because he can verify the obstruction, and his ruling is binding and resolves the dispute.