Lazy and cowardly writing
The acting was okay, but the writing was cowardly and lazy.
Cowardly in the sense that it doesn't deal with the hard parts, whenever there's a part of the dialogue that is hard to convey realistically, it just cuts away to another scene. Wtf is up with that? I want to hear what they say, I want to see how they deal with stuff. But, no, instead they just cut. I could do a movie script like that, too; if I just avoid the difficult parts.
And lazy in the sense that 50% of the drama is derived from Tommy's inability to just simply say “No, Sam, I didn't fuck Grace”. I mean, realistically in life, this movie would never happen. It's like the lazy writing in comedy TV sitcoms where all the action is a product of some stupid lack of communication that would only ever happen to dumb, emotionally immature 14 year olds. I mean, he didn't have sex with Grace, so why couldn't he just say that? He would not be lying. Sam had PTS from the war, sure; but anyone else mentally unstable or not would have thought Tommy had indeed had sex with Grace when he went to so many lengths to just avoid answering a simple question.
There's also the whole deal with the father, and whatever crime Tommy committed that don't lead anywhere.
Overall, a very disappointing movie, that had some potential but couldn't be arsed to put in the effort.