Does the movie explain... [spoiler]
I wasn't watching very closely, so maybe I missed this.
Charlie apparently recognizes Jacob after the accident. Why isn't she immediately suspicious? What are the odds that this guy she met in the city would happen to be on this isolated, rural road? I imagine this would have been a topic of conversation the first moment the husband leaves them alone, and yet they hardly mention it.
I'm not even sure the husband's plan makes any sense. What was the purpose of hiring Jacob to seduce his wife at all?