Knowing what I know about why the emperor’s wife’s age is important, I can see that they’re trying to build it up into a mystery that we will slowly unravel, but without that knowledge it definitely seems like just a running gag
I have no knowledge outside what's been shown in the episodes, but I think it's fairly obvious that the age is some specific condition from his curse (or similar thing). At the same time, the age gap is definitely pandering to a specific audience. The author knows exactly what they're doing, it doesn't matter if there is some in-story pretense. For better or worse, this is the story they wanted to tell.
Jill did establish that their relationship should be platonic, which is nice. Hopefully that's not just a front. The fact that the Jill is mentally older does help make it a little less gross (but at the same time, it feels like the author is trying to make an excuse for degeneracy).
It was nice to see Alicia actually acting like an antagonist.
Also the timing at the end got a laugh from me: