I just listen to this song over and over again, and while it has that melancholy melody, it also has some glimmers of hope in the refrain. "Single Again" is Mariya Takeuchi's（竹内まりや）18th single which was released in September 1989. Although it can remind people of those sad relationship breakups, it was actually used as the 8th ending theme for that Japanese TV chestnut, "Kayo Suspense Gekijo"（火曜サスペンス劇場...The Tuesday Night Suspense Drama） which kinda makes sense since getting thrown in jail pretty much guarantees solitude (well, unless one has seen "The Shawshank Redemption" among other prison movies). However, Takeuchi's original aim with the song was to reflect a woman's feelings after finding out her beau's indiscretions.
"Single Again" peaked at No. 2 on Oricon and ended the year at No. 22. It was a very long seller as it ended up in 50th place at the end of 1990. The song eventually also ended up as a track on Takeuchi's 8th album, "Quiet Life" which came out in 1992.