All of the episode titles in season 8 are lines that were said in season 1. The episode title comes from a line said by Damon Salvatore to Katherine Pierce (masquerading as Elena) in the season one finale Founder's Day (2010)
It looks like Damon is reading the second book of the Fifty Shades trilogy - Fifty Shades Darker, in the hotel room with Sybil and Enzo. Obviously he got hooked after the first part he read in s8e1.