I always have the guide box on when directing. And I make sure any scenes, especially with tappable overlays, fit inside the box, out of consideration for tablet users. It doesn’t matter how many or how few there are, you don’t want that one tablet reader trying out your story and leaving because they can’t see anything.
I think you should explain this to your partner. The gap may not be aesthetically pleasing, but it’s better than not caring about others and their reading experience whatsoever.