1845, French, literally "suffer sorrow;" one who is in a subservient position and must listen to or share another's troubles, specifically "a woman who acts as a paid companion to an older woman."
Online Etymology Dictionary, © 2010 Douglas Harper
Examples from the Web for souffre-douleur
Youre only too willing to offer yourself as a souffre-douleur on all occasions.The Dull Miss Archinard
Anne Douglas Sedgwick