Is it more befitting to return to the wife who is asking for that, or to remain abroad to help the father marry off the brother?

It is permissible for a husband to travel and be absent from his family for legitimate purposes for a period not exceeding six months. If the period exceeds that, he must seek his wife's permission. This is based on what was reported from Umar ibn al-Khattab, may Allah be pleased with him, who set the period of a soldier's absence at six months, and Imam Ahmad affirmed this. Sheikh Ibn Uthaymeen mentioned that there is no blame on the husband if his wife allows him to stay away for more than six months. However, if she demands her rights, he is not permitted to be absent for more than this period except for an excuse. The husband should return to his family to fulfill their rights and care for them. Obedience to the father is not obligatory if he orders remaining abroad, because that would neglect the wife's right, and "There is no obedience to a creature in disobedience to the Creator."