I don't have the issue, AFAICT.
Lots of ladies say their shoes fit tighter during the part of their biological cycles in which they have more fluid content, and foot size is well known to get larger during and to some extent after pregnancy. But why would a guy's fit vary from day to day?
The only thing I can think of is that when you have been standing on your feet a lot, your feet are supposed to change size. E.g., some people claim that feet expand over the course of each day if they are standing or walking. I wonder if some people's arches also gradually collapse over the course of the day under load. In either case, fit might depend on time of day, and what you have done during the day, even for a guy.
I don't know if either explains the issues faced by Ethereal Ice's husband. One would have to experiment, and take detailed size and shape measurements after various patterns of standing and walking.
Nike has made skates with inflatable bladder that are inflated to fit against the feet, which might adjust. They never caught on much in the figure skating world - maybe because Nike figure skates are only for beginners. I'm not sure if an inflated bladder allows for enough control for figure skating...
Baring that, at least one skate boot technician I know sometimes makes more than one insole to handle variation (e.g., for female cycles, or for childhood growth), as Riley suggests.