Like in Lisa Cholodenko's The Kids Are All Right, Concussion portrays a modern gay relationship that's revelatory in its normality. There's no trace of schoolboy sniggering or high-minded political statement in Abby (Robin Weigert) and Kate's (Julie Fain Lawrence) marriage – it's portrayed as being just as rewarding, frustrating, freeing and restrictive as any modern coupling between adults.

That's a good thing, because it lets Concussion get on with the story, and you aren't left wondering if writer/director Stacie Passon is sending us a social message. You could in fact take the given existence of the relationship as a message – simply that gay people have the same problems and failings as the rest of us in trying to make relationships work.

We don't even see the event that gives this film its name, but after showing us Abby and Kate's warm family life at home with their kids, suddenly everyone's leading Abby back the family minivan after a baseball game where she's taken a nasty blow to the head with a ball.

Until then, we've had a slight sense of how tired she is with being a stay-at-home mother and wife and having to be part of the fold of gossipy neighbours, but the blow awakens a new sexual hunger in her she doesn't know what to do with. After a brief, mostly seedy visit to a female prostitute, circumstances put it within Abby's power to work as one herself, and before she knows it she's earning hundreds of dollars per visit to sleep with women, from a sweet, heavy-set and nervous college freshman to a bi-curious friend from her neighbourhood clique.

The resolution isn't as important as the rest of the story and after awhile the movie doesn't really know what to do with Abby's plight except for the obvious (although it comes to a head with far less anger and pain than the rest of us have any right to expect in the same situation).

The long, slow, drifting approach in everything from the script to the camerawork doesn't do the movie any narrative favours, except to make Concussion look like a starkly beautiful high-end homewares catalogue. Passon has a good eye for shape and form and the honest, lived-in bodies and faces of middle-aged Abby and Kate are as beautiful as the trappings of their upscale urban New York lives.

But there's also a total absence of colour that does the movie a disservice – everything is set in muted whites and autumnal browns that only make the proceedings feel even more leaden. You'll find yourself waiting for something to happen or at least for the whole thing to speed up more than once.