How can one reconcile the statement that a husband must have intercourse with his wife according to her need and his ability, with the statement that he is not obligated to respond to her every request, even if he has no excuse? And what is the meaning of a man being the "owner of the private parts and having a degree above"?

A contradiction between Imam Al-Nawawi's statement and a ruling that obligates the husband to fulfill his wife's needs is possible. However, there is no contradiction between the husband not being obliged to answer his wife every time she calls him for intercourse, and the obligation to have intercourse with her according to her need and his ability. Therefore, if the wife is in need of intercourse and the husband is able, he is obliged to fulfill her need. The matter is tied to the wife's need, not to her request. The estimation of need is not limited and is determined by the couple according to circumstances, and the original principle is that the relationship should be built on love and mercy. The phrase "the husband owns the private parts" does not mean purchase, but rather the permissibility of enjoyment. The degree that a man possesses necessitates guardianship (qawamah), and it does not mean preferring him over the woman in everything or undermining her rights. The original principle is equality in rights and duties, except that the man has the degree of guardianship. And Allah's saying: "And due to them [the wives] is similar to what is due from them, according to what is reasonable. But the men have a degree over them," indicates encouraging men to good companionship and generosity towards women in wealth and character.