I’d seen this 1920 photo of the Wilsons previously, but hadn’t been able to place it. The mantel looks most like the president’s study in today’s Treaty Room, but the desk would need to be facing the window, which is backwards from what is shown in a slightly earlier picture. It’s not flopped, or their wedding rings would be on wrong and the window light would be at his back. Perhaps the photographer coaxed them into moving the desk to the other side of the room to take best advantage of the light.
Any other guesses?