What is to be done when a husband has intercourse with his wife during the daytime in Ramadan and claims not to remember the incident, while his wife is certain it occurred?

If a husband and wife engage in intercourse while they are unaware of what they are doing—such as when they are asleep or between sleep and wakefulness—there is no sin upon them, based on the Almighty's saying: "And there is no blame upon you for that in which you have erred, but [only for] what your hearts intended." However, if the wife becomes certain that intercourse occurred and it was by her choice, and she was not overpowered, then she must make up the fast and repent to Allah. Regarding the obligation of expiation upon her, there are two opinions.