The movie starts off wonderful. Acting is great. You really see the love these people share and how/when it starts to change.
However, the main actor has pretty much no character arc. They could have done so much. They had so much potential, but it just falls flat. He just acts and behaves terribly and yes, it was obviously intentional, but it was a bit over the top and unimaginable at times. Very dramatic. Where it didn't need to be, making it rather unbelievable.
The movie definitely starts off a lot better than it ended. They built it up really well, with a lackluster follow through.