After watching this film and being completely in love with every frame and every character, I read a couple of reviews that took issue with the subject matter, accusing it of just being about privileged white twentysomethings who didn't have real problems.

Don't believe a word of it. A movie about a crumbling marriage indeed doesn't sound terribly exciting, but neither does a story about a kid learning to be a jazz drummer under the tutelage of a brutal teacher, but Whiplash was one of the most gripping movies of 2014.

Take This Waltz reminds us movies are all in the telling, and if the script, characters and the actors portraying them draw you in, it will make the story – no matter how mundane or small scale – feel alive.

I wasn't just drawn in, I fell hook, line and sinker for the travails of Margot (Michelle Williams), Lou (Seth Rogen) and Daniel (Luke Kirby). Almost all of it is down to Williams herself. This movie was enough to make me think she's destined to be the new Streep – she's certainly the best actress of her age on screens anywhere. What she can do with a gesture, tilt of her head or glint in her pixieish, smiling eyes makes her contemporaries seem like histrionic hacks by comparison.

Even though a billion marriages cause their participants pain every minute of the day, I got lost in her face and her voice, understanding just what the character of Margot felt – that unhappiness in marriage becomes the whole world to the sufferer. That's what I mean about being drawn in. Even without alien invasions, robot armies or a zombie apocalypse, it was a universe of unhappiness for just one person, and Polley's script and Williams' mastery over performance put you right in there with it.

A well-to-do Toronto couple, Lou is on the verge of breaking big as a cookbook author, and Margot is a writer who we gradually discover would love some more attention and seduction from her husband.

But when we first meet her, she ends up on a plane next to the forthright Daniel. It's obvious the two share a flirtatious attraction, but she has no intention of following through.

So when it turns out he lives right across the road from her, it seems life will be a bit more difficult. Margot tries to get on with her life, enjoying her and her husband's beautiful house even if it isn't filled with as much love as she wants, and the extended family members around them are as warm and realistic as Lou and Margot are (including a brilliant Sarah Silverman).

It's hard now to remember exactly what went on in the actual plot, but Williams deftly drawing you into Margot's quietly roiling emotions leaves an indelible impression. As she struggles with her growing attraction to Daniel she worries that the lack of attention from Lou might just be the same marital stumbles everyone goes through. It's a story as old as the hills, but few films make you experience it so wholly with the characters.

Watching Williams convey everything so plainly just with what she does with her stance and face is a joy to behold, not just because it's a pleasure to watch her unique physical beauty but because somewhere along the line – maybe after the film's over – you realised you've watched a performance of rare power.

Rogen isn't as skilled a dramatic actor, but he doesn't need to be. All the role of Lou calls for is the same improv-style authenticity he's already great at, only without the jokes.

Polley also does something interesting with the narrative by not shying away from the second relationship rather than cutting away at the ride into the sunset/newly in love moment. I'm still not entirely sure what it does, but when we leave Margot, I've never wanted a film to keep going so badly before, just to assure me she wouldn't end up heartbroken all over again.

I've loved almost everything both Polley and Williams have been associated with as actors or filmmakers, but nothing prepared me for how much I loved this.