First you might want to have a look at some of Glasner's other films. THIS IS LOVE: story too convoluted, but good acting. MERCY: might be similar, I'm keen to see it myself. It's not easy to name a similar film. Content-wise it reminded me a bit of HOMO FABER of which I only know the novel (determinism, fatalism). Marc Didden's BRUSSELS BY NIGHT has equally dark realism, but is not as convincing. The Korean ONE FINE SPRING DAY is a subtle exploration of how its protagonists find each other, then slowly withdraw from each other. But it is in no way as bleak as FREE WILL. SOMEWHERE is slow, lingers on moments, scenes & characters, but is again not as bleak. THE WHITE RIBBON is similar in pace and seriousness, but with Haneke's style it's quite a different experience.
Thanks. I've not heard of most of those so thank you, I look forward to watching them!! I still have yet to try his earlier work, as I had heard it wasn't up to the level of his earlier films.