Reading to fairy house, is this a bug or intentional?

My Sim went home with her date & while she's fixing some food, he went over to her fairy house & is reading it a story. It's empty, but he's showing it pictures in the book and reading in a very animated way. 

Is this a bug? Or is this intentional?

If intentional, why would he do this? Is the house alive? Is it some crazy personality quirk I haven't found yet, like when erratic sims talk to invisible people? 

If it's intentional, then it's sad, because I can't get my Sims to read to their children unless they're reading them to sleep (if they kid isn't on a bed the parent gets/takes out a book, walks to the chair, then put the book in their inventory and drop the action from the queue. This has been ongoing for a while).