What is the ruling of Islamic law concerning someone who broke their fast while traveling to meet their Christian wife and had intercourse with her? Is he required to make up for the fast (qada'), or both make up for it and offer expiation (kufara)?

If a traveler has sexual intercourse with his wife during the daytime in Ramadan, there is no sin upon him and no expiation is required. He only needs to make up that day, in accordance with the Almighty's saying: "And whoever is ill or on a journey - then an equal number of other days."