Up against The Wall: Why this novel is not filmable

On suggestion of JS we watched the recent Austrian film The Wall (Der Wand) but found unfortunately that our tastes occasionally, if rarely, differ. Put quite simply, The Wall tells a story of a woman who goes off w/  two friends to an Alpine hunting lodge; when they head off for the village, she finds that she is suddenly living in complete isolation - a glass-like, impenetrable wall has manifested itself all around her - entrapping her and the few animals in her vicinity. She is completely cut off from all civilization; she sees some other people in a nearby cottage - but they are on the other side of the wall, dead - as if stricken suddenly by a death ray. That's the premise. The movie shows her living through what appear to be about 2 years of her life, bonding with her dog and with some other animals, using all of her survival skills - she must have been raised on a farm, although the film tells us absolutely nothing about her background (the source novel may tell more). In fact, one of the true oddities of the film is that she expresses no fear or despair about any people she may have left behind on the other side of the wall, and in fact she more or less submits to her entrapment - she doesn't appear willing or able to see if there's a way out. OK, this is not meant to be a horror story (although it does further emphasize the message about about thousand horror films: If friends ask you to join them for a weekend in a remote cottage, don't.) or an escape story a la say Deliverance - but it's an allegory of some sort: We are all "entrapped" on our planet and we must build symbiotic relationships with nature and with animals in order to survive and prosper. I think that's the point; what isn't the point is any explanation as to what's happened. I kind of thought we were in a film like The Village, and there would be a surprise rescue or breakout at the end. Don't hold your breath. A strength of the film is the absolutely beautiful cinematography. A weakness - as, after the first two minutes, there's only one human character, virtually the entire film is told in her voice-over (she's writing a journal). That works in the novel, perhaps, and maybe there's no other solution, maybe this novel is unfilmable, but it makes the narrative very slow - feels like this is an audiobook with pictures.