In the U.S., “Love Is a Stranger” is known as the follow-up single—the song that scooched its way into the Top 40, partly by drafting off the hype from its chart-topping predecessor.

The movie “A Love Song” is kind of like that. In a filmmaking universe where Michael Bay and Zack Snyder seem to be in a battle to see who can damage more eardrums, first-time feature writer ...