According to Jim: Season 5, Episode 2

5 - 2: The Tale of the Tape: Part 1

Jim worries that Cheryl's romantic expectations will increase when his new brother-in-law, Ryan, showers Dana with flowers and gifts. But then Jim learns that a special blues tape Cheryl supposedly made for him when they were dating, and that made him fall in love with her, was actually made for her by an old boyfriend