Complex sentence: It was written about Jane Asher, McCartney's girlfriend for five years, "You don't look different, but you have changed," the lyrics declare, reflecting his dissatisfaction with her and their relationship.
Split into simpler sentences: It was written about Jane Asher, McCartney's girlfriend for five years. The line "You don't look different, but you have changed" reflects his dissatisfaction with Asher and their relationship.