One of those by few of those for few of us

Synopsis found from the net:-

Grieving investment banker Davis Mitchell (Jake Gyllenhaal) returns to work after losing his beloved wife in a tragic car accident. After writing a letter to complain about a vending machine, Mitchell receives a phone call from Karen (Naomi Watts), a customer service rep from the company. Karen becomes moved by his complete honesty, while Davis finds someone to lend a sympathetic ear. As his new friendship with Karen and her son grows, Mitchell finds the strength he needs to rebuild his life.

My interpretation:-

Man marries out of going-with-the-flow, he doesn't really know why he married his wife. Things just happened. She was a nice person. 

One day, they met with a car accident and his wife died. This man couldn't grieve, he doesn't really feel a thing. He has an anal nature. He wrote a compliant letter to the vending machine company when the packet of M&Ms he paid for got stuck. He wrote a lengthy letter and the customer service lady responded with a phone call. This guy, he asks point blank questions that most people have not given a thought to. Obsesses with details, queries about why things breakdown. Annoys everyone around him. Until finally he has a meltdown and proceeded to demolish his life, his high flying job, his posh house. Finally, he begins to feel again. The last time he cared for something was when he was a young boy in school, racing among his peers. He had been a walking zombie for most part of his life. Finally, he realizes that he had loved his wife, it was just that he hadn't been paying attention to her nor to their marriage. You know, just drifting by. After he figuratively demolishes his life, he went on to set up a foundation for children with special needs in his late wife's name (something that she cared about when she was alive), he begins to heal and live again.