Là-Bas by Joris-Karl Huysmans

Next day his ferment had subsided. The unknown never left him, but she kept her distance. Her less certain features were effaced in mist, her fascination became feebler, and she no longer was his sole preoccupation.

The idea, suddenly formed on a word of Des Hermies, that the unknown must be Chantelouve's wife, had, in fashion, checked his fever. If it was she -- and his contrary conclusions of the evening before seemed hardly valid when he took up one by one the arguments by which he had arrived at them -- then her reasons for wanting him were obscure, dangerous, and he was on his guard, no longer letting himself go in complete self-abandon.