“Heart at the Door” is an unreleased song written by Melanie Martinez and Syience in 2013. It was registered later that year.

In 2016, when Melanie posted lyrics of “High School Sweethearts”, fans began to speculate that they were lyrics from “Heart at the Door”. Melanie cleared up the rumors on Instagram, stating that “Heart at the Door” was a song she made “a long time ago” for another artist.

Despite the song not being intended for Melanie’s own projects, she likely recorded it for pitching to the other artist.