Of course I forgot to mention that at the end she's still thinking of him on the train and him in the car, so he drives like a madman to meet her at the station in Paris when her train arrives. And they embrace, and we know everything's going to be fine.
See, it's so hard to let go of even serial killers when they seem like the type to do that.
I guess we'll just have to see.
In the meantime, life.