If you look at the presidential schedule, you will learn that King Barry actually attended a fundraiser after the Kimmell show, and on the following day, he flew on to Phoenix where he received a briefing on “veterans issues”, and then returned to DC.
Note that the event in Phoenix is the “official business” that is used to justify the trip, and and the billing of the majority of the expenses to the taxpayer.
The taxpayers might well have not been directly billed for the queen’s expenses, but they paid a price anyway for the security arrangements and the double hit on the people of Los Angeles who had to endure the disruption and traffic jams that the king and queen always cause when they arrive.
Now, if Michelle Antoinette had accompanied the king, that means she would have to have been accommodated in some way for the night, and that would have interfered with the king’s “other plans”.
And that, almost surely, was the real reason why they didn’t travel together.
Serfs, you must remember, the rules only apply to you, not to the “elites” The Ministry of Truth is always correct.