Breillat said "[t]his is a film about desire and seduction. The heroine keeps going to the limits of her desires. She repeatedly seeks new experiences, because desire soon fades." Also said: "[a] crude film, of an intense, moon-like beauty, a sexual film with a series of cutting-edge scenes on carnal relationships, a tale of love and desire in their raw state..."
I saw it as a cautionary tale. Solange is trying to liberate herself, or thinks of herself as liberated, but it is a man's world and she has been socialized by it, so there will be no freedom until she frees her mind of all the manshit. Desire and "experiences" and clever talk are not paths to freedom.
The existential sense that pervades this film unfortunately for me begins with a highly raised bar, people with too much money and too much time, which may in its own way produce the really stark existential result. As far as we are gone down the road of ennui since this film, it is difficult to get excited about another voyeur experience. I write this as a true fan of Breillat though, especially her fairy tales.