What is the religious ruling on a father forcing his daughter to leave her fiancé, under the pretext of demanding financial requests beyond his means, knowing that the fiancé is characterized by good morals and religious commitment and is doing his utmost?

The default is that a father is keen on his daughter's interests. However, if the suitor is righteous and you desire him, your father does not have the right to prevent you from marrying him without a valid reason; otherwise, he would be an 'āḍil (one who unjustly withholds consent). In such a case, guardianship transfers to the next in line among the guardians, or you may refer your case to a judge. It is advisable to reach an understanding with your father or to have someone mediate and speak with him. If he insists on refusing, then be patient, unless there is harm in not marrying him. In that situation, you may marry under the guardianship of the closest relative after your father, or refer the matter to the judiciary, while still being obligated to honor your father and treat him kindly.