A love song by Gustav Mahler is at the center of composer and Festival Artistic Director Marc Neikrug’s new stage work, A Song by Mahler. “Liebst du um Schönheit” (“If You Love for the Sake of Beauty”), from Mahler’s Rückert Lieder, is “a key element to the drama,” Mr. Neikrug says, and, as it “embodies the message of love as an aspiration, a self-embodied posture, and a state of being,” speaks to the emotional core of the work as well.

A Song by Mahler centers on the changing realities of two characters: “a concertizing singer who is diagnosed with early-onset Alzheimer’s” and her husband, “who is also her accompanist,” Mr. Neikrug writes in a program note. The work—which features the talents of mezzo-soprano Jennifer Johnson Cano, baritone Kelly Markgraf, clarinetist David Shifrin, and the FLUX Quartet—“is not an attempt at documenting the myriad aspects of the disease,” he says. Instead, it’s “an attempt to address the specific emotional evolution of this couple, touching on their love and their particular relationship to music.”