She wrote it with Laura Veltz, Jordan Lutes, and its producers Warren "Oak" Felder, Keith "Ten4" Sorrells, Alex Niceforo, and Mitch Allan.

The song was received with positive reviews from music critics; many of them praised its lyrical content and highlighted it as a standout on Holy Fvck.

[1] On June 6, she announced her eighth studio album, Holy Fvck, along with its cover art, release date, and with a link to her official store where fans could order physical copies of the record, but did not immediately reveal the tracklist.

It was written by Lovato, Laura Veltz, Jordan Lutes, Mitch Allan, Keith "Ten4" Sorrells, Warren "Oak" Felder, and Alex Niceforo, and produced by the latter four.

[9] "Happy Ending" was described by Mark Beaumont of The Independent as "a rousing slab of grunge pop soul-searching" with Lovato confessing: "I miss my vices [...] demons are calling and tearing me to shreds".

[13] For Insider Inc., Callie Ahlgrim ranked "Happy Ending" as the second best song on Holy Fvck, adding that it boasts the "most vivid and heart-wrenching" lyrics in Lovato's music catalog.