Songfacts®:

• The Trews made a name for themselves in Canada with their first album, House of Ill Fame, in 2003. Success meant more work and more pressure, which took its toll on lead singer Colin MacDonald. He wrote "So She's Leaving" as a response; the song became the first single from their next album, Den of Thieves.
  
  "That song was just a complete stream-of-conscious rant," he said in a Songfacts interview. "As much as this might sound like a total cliché, it was about just being totally burnt out on an insane tour schedule and being in a really tumultuous relationship back home at the same time. I just wrote it in like five minutes over this killer riff that the guys had going on in the jam room."
• Colin MacDonald had been listening to Elvis Costello's Blood & Chocolate around the time her wrote this, which was an influence on the song. "That record blew my mind," he told Songfacts. "He's really into the savage breakup songs."