The film worked.
Comparing the beginning of the film, where Suziey and her roommate look out from their rooftop at the lights of L.A. (I presume) discussing the terror of the accidental world, with the ending, where she and someone else look from the same vantage and experience that world, you can say that the rest of the picture is a machine taking us from one point to the other. Every action, however minute -- and they seem really minute -- is a cog in that machine. Less than a slowburn, it really is a no-burn, until the landscape of little worries and vague potential threats that is most women's lives erupts into the worst possible outcome. I can't say I liked the movie a whole lot, but I will say that a whole lot more intelligent thought went into making it than seems to be going into watching it. If nothing else, think a little about the title; that at least was no accident.