" A man when he is making up to anybody can be cordial and gallant and full of little attentions and altogether charming. But when a man is really in love, he can't help looking like a sheep. Now, whenever that young man looked at you, he looked like a sheep. I take back all I said this morning. It is genuine. "

― Agatha Christie , The Mystery of the Blue Train (Hercule Poirot, #5)