An allegory of theatre?
Do you think this movie could also be an allegory of theatre (or film-making or any other form of dramatic art)?
I understand that Martha's and George's characters are obviously, deliberately and intentionally created to perform their fights in front of their little audiences in order to show us how delusional and showers are they, but I also think there is something more.
Nick and Honey are so conveniently (just as George mentions too) brought to the whole story with their main characteristics resembling those of the leading couple's, that remind me of a couple watching a movie and projecting their thoughts and problems on the heroes they're watching.
Furthermore, every time they provide an information about them, this information is used to move forward the ''in-movie plot'', a plot that keeps changing and twisting, manipulating their emotions making them uncertain of what's true and what's not, like a good thriller. Even George and Martha behave like histrionic screenwriters saying things like ''you are not supposed to know (if we are lying or not)'' in many occasions.
Finally, after the revelation of the last scene, where Martha behaves as an improvising actor and George as an unseen (due to the composition of the frame) director giving directions and changing the plot-points, Honey is reaching the catharsis interpreting the story as if she should have a baby and Nick solves the mystery and exposes the facts.
There are many more references and details (like the book's plot, that itself keeps appearing also as fictional and as reality, merging the realities and confusing the young couple), the fact that there are no ending credits (as if the real movie is over long before the actual movie is over), the absurd plotline of the imaginary son that emphasizes the surreal and symbolic nature of storytelling and the overdramatic and excessive way things are adapted for the screen, etc.
So?