What should a girl do after her fiancé (her cousin), to whom she is عقد قران (religiously married), confessed that he no longer sees her as a wife, feels no desire for her, and is thinking of separation, knowing that he is a religiously committed man and she does not want to separate from him?

What the husband said is not considered a divorce. As long as divorce is merely an idea for him, the wife is still his wife. She must obey him as a wife, and he has his rights as a husband. She should ask him not to divorce and explain to him its negative consequences, and that building homes does not depend solely on love, but also on character and religion.