Is praying for the return of one's husband after divorce—under the circumstances mentioned—considered an transgression against Allah's decree? Is it possible for him to return, and what should I do?

The questioner erred by seeking divorce without a valid reason and by listening to people's talk. She must repent and seek forgiveness. A woman divorced before consummation is considered to have a minor separation (baynunah sughra) and can become lawful again through a new contract and new Mahr. She does not have an waiting period ('iddah (definition)), based on the Almighty’s saying: "O you who have believed, when you marry believing women and then divorce them before you have touched them, then there is no 'iddah [period] for you to count concerning them. So provide for them and give them a gracious release." There is no harm in her supplicating that Allah reunite her with her former husband, but it is better for her to forget him since he is engaged again. What happened might be good for her, for "perhaps you dislike a thing and it is good for you; and perhaps you love a thing and it is bad for you. And Allah knows, while you know not." She must fear Allah and perform righteous deeds, for through this, good is attracted and calamities are repelled, as the Almighty says: "And whoever fears Allah - He will make for him a way out And will provide for him from where he does not expect."