What should a young man do who works in an Arab country and sends large sums of money to his family, which delays his marriage, and his father is well-off but does not help him? And would he be unjust if he asked them for help after fulfilling his obligations?

There is no harm in saving money for marriage and its expenses if the family has sufficient financial support. It is better to combine saving with sending some money to the family. There is no sin upon one who advises a man to save his money for marriage if the family is not in need of the money sent, provided that this does not lead to cutting off ties of kinship or disobedience to parents.