What is the ruling on a young man insisting on marrying a foreign girl and refusing to back down from his decision, despite his mother's strong rejection and the deterioration of her psychological state due to this matter?

If a mother prevents her son from marrying a specific woman, and the prevention is for a valid reason, then it is obligatory for the son to obey her. It is feared that the brother's disobedience to his mother in this case would be an unlawful act of disobedience (ʿuqūq), and he must be advised and reminded of his mother's right over him. An attempt should be made to convince the mother to approve her son's marriage, and some wise individuals should be mediated to reconcile between them.