Does a man have intercourse while he is asleep without his awareness, thereby invalidating his fast? And what is the ruling regarding the wife's action in this situation?

The fast of the man who ejaculated is valid, and if he makes it up as a precautionary measure, that is good. As for his wife's fast, it has been broken, and she must make it up. She also owes expiation according to the majority of scholars, and she must repent from this forbidden act.

As for the man who ejaculated, he is not obliged to offer expiation according to the correct opinion, because he is in the position of one compelled, and this is supported by the statements of Ibn Qudamah and Al-Ruyani.