I'm using the original French title of the film, because although it's adapted from the comic Blue is the Warmest Colour (which is great), this is a different beast. Abdellatif Kechiche combined the source material with another story he was developing, about a teacher who stoically sticks to her duty despite her turbulent private life. So while chapter one remains quite close to Maroh's outline, chapter two goes down a different road.
Have to say I found the second half a lot more interesting, and I don't think it's just because I was already familiar with the first half. For all the endless takes and improvisation, Kechiche isn't shooting a documentary. His frames are carefully composed, as are his scenes – and much of the sexual awakening stuff at the beginning feels like heightened high school drama, removed and idealised away from the awkward, messy reality.
The film is notoriously long, and I think some of it is bloat. It tickled me to learn that Kechiche worked with several editors when cutting – I imagine he rather enjoyed the divide and rule opportunities this created. But the most fraught editing choice I agree with. Some critics found the explicit sex scenes dragged on into the gratuitous, but I think they are necessary. I'm oversimplifying only slightly when I describe Adèle and Emma's relationship as being built on their physical passion for each other, and destroyed by everything else. Part of this is class – while they live in the same town they are drawn from different cultures. But they also make their own destinies, and the film makes clear that their interests and goals diverge.
But understanding that iron grip of sexual obsession is crucial to justifying the extraordinary scene in the bar towards the end – the first time they see each other after the break-up. It is heartrending because both women are desperate for that intimacy once again. Adèle is delirious and collapses into grovelling, but Emma is mature enough to tear herself away from temptation. She loves someone else – Adèle is no longer the centre of her story.
This is a blow the comic could not deliver (it goes in a slightly forced bereavement direction instead). Adèle is hollowed out at the end of the film, giving even a potential race for your love the slip. The French language title provides the only source of comfort: this is only chapters one and two. Adèle walks away from her first relationship, and into a life comprised of many other chapters.
The closest parallel here is probably Boyhood, which I managed to see in the cinema and felt like I could watch go on for an entire lifespan. Linklater's film also isn't a documentary – it is suffused with affect. But it tries to present the development of a character as completely as possible. Likewise we see Adèle eating, dancing, working, sleeping, cleaning, showering and cumming. We get a picture of a rounded personality (thankfully less privileged than the one in Boyhood). But at some point the film has to stop and the credits need to roll, even if we don't want them to.