Songfacts®:

• "Illicit Affairs" is a slow-building ballad about infidelity. Taylor Swift lays out the differing emotions of the secret tryst, from the sneaking around:
  
  Make sure nobody sees you leave
  Hood over your head, keep your eyes down
  
  To the evaporating emotions stirred by the illicit affair:
  
  A dwindling, mercurial high
  A drug that only worked
  The first few hundred times
  
  During the bridge, Swift explores the effects of the relationship being carried out in secret.
  
  And you wanna scream
  Don't call me "kid," don't call me "baby"
  Look at this godforsaken mess that you made me
• Taylor Swift first tackled the idea of infidelity on 2006's "Should've Said No," where she condemned a boyfriend who cheated on her. By Reputation's "Getaway Car," Swift was attempting to escape her own relationship by hooking up with someone else. This song finds Swift withholding judgment about the temptation to stray without ignoring the resulting heartbreak.
• Taylor Swift wrote and produced the song with her frequent collaborator, Jack Antonoff. The Bleachers lead singer also played percussion, bass, and guitar. The other instrumentalist on the track is Antonoff's Bleachers bandmate, Evan Smith, who played guitar, accordion and saxophone.