What is the ruling of Islamic law regarding a man marrying a second wife, despite his family's disapproval, due to a significant difference in academic levels between him and his current wife, in addition to her considerable lack of desire for the marital relationship?

Righteousness towards parents is among the greatest deeds after monotheism in Allah the Almighty. However, there is no obedience to a creature in disobedience to the Creator. If you fear falling into sin, then a second marriage is obligatory for you, and you must explain to your parents the danger of falling into temptation.

You must be just between the two wives. The Prophet, peace and blessings be upon him, warned against violating the rights of a wife and inclining towards one over the other. He, peace and blessings be upon him, said: "I declare inviolable the rights of the two weak ones: the orphan and the woman." And he said: "Whoever has two wives and inclines to one of them, will come on the Day of Resurrection with one of his sides leaning."

Helping one's family in obedience is one of the best acts of drawing closer to Allah. Their rejection of their son's second marriage is a help to Satan and opens the way for him to fall into sin. The purpose of marriage is to preserve oneself (chastity). While appreciating the first wife, cultural differences and a lack of passion may prevent harmony and the fulfillment of needs. Therefore, one must choose the second wife wisely, ensuring she is religious, treat them justly, and minimize the effects of jealousy.