When actress Sarah Polley, who spent her youth as “Canada’s sweetheart” for her roles in popular television series like Road to Avonlea, moved into directing, the results surprised many of her fans: Away With Her, a moving but clear-eyed drama that won Julie Christie an Oscar nomination for her performance as a woman adjusting to life in an Alzheimer’s facility. Polley was also nominated, for her script (adapted from an Alice Munro story.)

Her new film has divided viewers since its premier at the Toronto International Film Festival last year. A study of female sexual restlessness, it stars Michelle Williams as Margot, a Toronto housewife in a stable relationship with Lou (Seth Rogan), her husband of five years. There’s no reason for her to be unhappy. But she finds herself attracted to Daniel (Luke Kirby), an artist who has just moved in across the street.

Observational and leisurely to the point of being sedate (it runs nearly two hours), Take This Waltz moves imperceptibly between sequences of domestic calm and others that may be fantasies. Margot and Lou play faux-violent word games, flirt in bed, and get into seemingly meaningless spats. The comfortable banality of these scenes (Rogan displays an ability to be likeable without his standard boisterousness) contrast markedly with Margot’s meeting with Luke, which depends on coincidences so unlikely that you wonder if she is imagining them.

By the same token, some of the dialogue is so in-your-face obvious that you put it down to a screenplay uncertain that the audience will “get it”: “I’m afraid of connections,” she tells Luke at an airport, meaning getting from plane to plane, but of course we get the real drift. (And what to make of the fact that the first words in the film are “Everyone gather in the square for the public humiliation”?) Yet the film climaxes (I wish there was a better word) with a montage of sex scenes that demand a subjective interpretation.

It’s a compelling but demanding film, not for all tastes but unique among current offerings.

Watch the trailer for Take This Waltz