A short search here on trakt reveals that the idea for this movie is anything than somewhat original. However, I haven't seen the 2008 (Flemish) or 2010 (Dutch remake) version, nor maybe any other one that may exist under a different name.

But I must say a very intriguing story and one of the best movies I've seen in a long time. Mainly because of the great cast and their acting. What'd you expect from Karl Urban (Almost Human, great series, cancelled way too early) or Eric Stonestreet (Modern Family).
The story is nicely told with flashbacks and had me guessing what happened and who is responsible and still was able to surprise me. Although it should have been kind of obvious that it was that person. James Marsden and Wentworth Miller are also very well known faces and fit in here very well.
The great thing about this story is that basically every single person would have a motive.
And as if one plot twist wouldn't be enough it houses another one that bugged me as soon as it happened. The insulin incident.
While it is heavy on dialogue, explaining a lot and not action driven, I'd highly recommend it, if you don't know the story yet and prefer story - although not overly complicated - over action.
Surprisingly it has a rather averaged rating and a bad one on Metascore, where it is rather criticially panned. Some of the criticism is valid, though. Especially regarding the wives, but well.
See for yourself on what side you are on.

A group of five middle-aged guys share the only keys to a private, secret condo expressly for their extramarital affairs. One morning, a bloodied dead woman is found in the bedroom and the arguing and finger-pointing begins. This seemingly has all the ingredients for a great small-scale tension cranker, but ambition gets the best of it, it tries to go large, and the whole thing blows to bits on the launchpad.

It's terribly acted, for one, which is something of a surprise given the healthy careers enjoyed by its stars. Karl Urban and James Marsden are well-seasoned, even if they aren't exactly leading men, and Eric Stonestreet - while miscast in a very adult role - should at least know how to carry himself on the screen. Instead it's amateur hour, where limp first-takes abound, and the finished product is something I would expect from a bit of Cinemax softcore, not a polished big-budget production.

I don't care about, or even remotely like, a single one of the characters, the writing goes around in circles seeking every possible twist, and the ending really doesn't even make any sense. Points for the concept, and for a few scanty bits of eye candy, but otherwise this is a major whiff.