How can a son reconcile his desire to marry a Jordanian girl with his Palestinian father's refusal due to differing nationalities, while striving for the pleasure of Allah and his parents and avoiding what is forbidden?

Obeying one's parents is among the most obligatory duties. If the father's rejection of the girl is for acceptable reasons, such as a defect in her religiosity or character, then you must obey him. However, if his rejection is merely due to a difference in nationality, and the girl is religious and of good character, then you are not obligated to obey him. Instead, strive to convince him or involve someone who can influence him. If he insists [on his refusal], there is no harm in marrying her, while being careful to honor him.