Gibbons. Bald Eagles. Swans. Just a few mammals that apparently mate for life. One group you won't find on that list, for whatever reasons, are humans. Massy Tadjedin's directorial debut examines a time in a young couple's life where they are both presented with temptation, albeit in different ways, at the same time.

Whilst at a trendy party, Joanna (Keira Knightley), notices her husband Michael (Sam Worthington) paying his attractive colleague Laura (Eva Mendes) quite a bit of attention.

She raises this observation with him when they return home, but it's not long before this discussion turns into a fight. Michael attempts to clear the air early the following morning, by apologising (although he's not entirely sure why) and serving his wife breakfast. Soon after though, he's off to Philadelphia on business, with Laura by his side.

Joanna doesn't have much time to think about what's happened, or what might well happen for that matter, because she bumps into Alex (Guillaume Canet), an ex of hers from her past in Paris.

With the pair away from each other for one night, they soon find themselves going down similar roads, with their final destination quite possibly being infidelity. But is it one that either of them reach?

I wonder if I would find her more attractive if she were blue...

It's no wonder that the talent involved with this film decided to jump on this project; it's the kind of material that is all character driven, allowing actors to really hone their craft. It's certainly a bold choice for Worthington in particular, as his career seems pretty much geared towards playing the consummate action hero. But the only clashes he suffers from in this film are emotional ones.

Once you get over the rather crowbarred in chance meeting by Joanna and her old French flame at the exact moment her hubby is out of town, what's left is a curious examination of a couple's commitment to one another being sorely tested, in different ways, simultaneously.

Michael's test involves a possible coming together with a new, attractive colleague. It seems, on the surface at least, to be nothing other than a physical connection.

Joanna's test however, is with someone that she not only cared about for some time, but still carries a torch for.

The film therefore revels in this moral ambiguity, offering the audience incriminating evidence on both sides, with the intention of asking the question: whose dalliance with infidelity could be considered worse?

It would be a far more interesting question posed if it were possible to care for any of the individuals concerned. Through no fault of the talented cast involved though, the characters they play feel not only removed from each other, but from the audience too. Without there being a connection of any kind with any of them, it's difficult to give a hoot over any of those involved.

The piece would probably have worked better on stage, in a nice intimate venue, but on film their plight doesn't offer up any reason to care about them or their marriage woes.

In that sense the film is like someone telling you about a couple you've never heard of before, going through this scenario, and expecting you to care as a result.

Perhaps part of the problem lies in the fact that all those involved lead seemingly comfortable lives. Michael and Joanna live in a chic New York apartment to die for, and have exciting, well paid jobs. We also don't get that much of a sense of them as a couple, as they are split physically fairly early on. Do they love each other deeply? It's difficult to tell. So when there's this disconnect between the pair from the off, it just makes it more difficult to invest any connection ourselves with them.

Ultimately the film's intentions were admirable, after all there's nothing wrong with putting a couple's reasons for being together – or not – under scrutiny, it's just a pity the film did so without any heart.