A couple is kidnapped, but the kidnappers have no idea that The Boyfriend Is A Psychopath

"No One Lives" 2012
A couple traveling cross-country encounters a gang of robbers led by Hoag. They kidnap the couple and demand access to their money. The woman commits suicide, and the man breaks free and kills one of the robbers. The robbers discover a girl in the trunk of the couple's car, who is the survivor of a previous massacre. The man begins to take revenge on the robbers, killing them one by one, and the girl joins him. In the end, the man kills all the robbers, except for one who manages to escape. The man also kills the survivor of the previous massacre, whom he had taken with him. The movie ends with the man leaving the hospital where he had killed the survivor and touching the arm of another patient who is wheeled in.