Robert Smith serenaded his wife of 34 years, Mary Poole, with The Cure’s “Plainsong” during a recent performance on the band’s ongoing “Shows of a Lost World” tour.

Robert Smith and Mary Poole Smith met when they were 14 in a drama class. The pair married in 1988, and he’s written quite a bit of music about her. Specifically, the classic 1989 song ...