I thought this too, found it very disjointed for a film.
I thought Natalie Portman was dreadful, completely wooden, don't get the hype about her at all.
To be honest, I just didn't like it, I felt dirty after watching it, I thought all the characters were horrible and felt no empathy for any of them. They were all screwing around, so I could care less if any of them hurting.
Was this by the same people that did the company of men? it has that same nasty undercurrent.