 The film also stars Charles Grodin, Judith Ivey, and Steve Lawrence and features cameo appearances from Merv Griffin, Dr. Joyce Brothers, and Loni Anderson.The theme song, "Love Comes Without Warning," was performed by the band America.When shy Larry Hubbard (Steve Martin), a greeting card writer, finds his girlfriend Danielle (Robyn Douglass) in bed with another man, he is forced to begin a new life as a "lonely guy."