Avril Lavigne has been making snotty records about skater boys and bitchy girls for almost a decade now. On her fourth album, she grows up. Being a 26-year-old divorcee will do that to you. Written and recorded as she was splitting from one of the Sum 41 dudes, Goodbye Lullaby trades brassy kiss-offs for a sobering dose of introspection. The music is more grown-up too: strings, down-tuned piano notes, and soft-strummed acoustic guitars are all over the album. Lavigne and her collaborations go for a more direct line to traditional pop here, filling songs with big, hooky choruses. After the pushy throwback “What the Hell” (“You say that I’m messing with your head, all because I was making out with your friends”), Goodbye Lullaby gets down to serious business, throwing out Lavigne’s messy personal life in “Push” (“Maybe you should just shut up when things get tough,” she sings. “This is love”), “Wish You Were Here,” and “Goodbye.” And she thought things were complicated before?