[2] In Europe, the song reached the top-five in more than ten countries while peaking at number one in Austria, Belgium (Wallonia), Romania, Sweden, and Switzerland.

"Un-Break My Heart" has been covered by several artists, including American alternative rock band Weezer on the album Death to False Metal.

"Un-Break My Heart" was conceived from its title, and, according to Warren, "it popped into my head, and I thought, 'I don't think I've heard that before, that's kind of interesting.'

"[4] When Warren played the finished song to Arista Records' future president (2000-2004) L.A. Reid, he thought it would fit Braxton's then upcoming album.

[9] David Willoughby, author of The World of Music (2009), said a few phrases such as "Don't leave me in all this pain" are sufficient to reveal the "sadness and the longing" in the song.

As noted by Jose F. Promis of AllMusic, the songin its original form, was a massive adult contemporary and pop hit, and, with its larger-than-life chorus, worked equally well as an unstoppable dance number, even if the vocals were never re-recorded.

[16] MusicOMH contributor Laura McKee considered it "an easy listen" version "that encapsulates the passion and meaning of the original but opens it up to a wider audience.

He added, "She maximizes the melodrama of David Foster's savvy blend of stately strings and soulful rhythms, móving from a dewy-eyed whisper to a diva-like belt with theatrical ease.

"[20] Bob McCann, author of Encyclopedia of African American actresses in film and television (2010), considered it "simply one of the most haunting R&B records ever made",[21] while Robert Christgau named it "miraculous" and explained "the miracle being that it's by Diane Warren and you want to hear it again.

"[22] Dave Sholin from the Gavin Report commented: "Most who hear this Diane Warren composition, which was produced with skillful guidance by David Foster, will need to take a few seconds before breathing normally again.

[24] In a 2015 retrospective review, Pop Rescue wrote that Braxton's vocals "really shine and she's given a real range from very low to powerful highs."

The reviewer added that "the music here, aside from the acoustic guitar, is absolutely secondary behind Toni's vocal prowess and the tender lyrics.

"[26] Richard Harrington from The Washington Post felt it's "less sung than confessed as Braxton slips into whispered regrets and second thoughts.

"[27] While reviewing the album, Stephen Thomas Erlewine of AllMusic said the songs produced by David Foster are too predictable due to their "slick commercial appeal".

However, Erlewine noted that Braxton "manages to infuse the songs with life and passion that elevates them beyond their generic confines" due to her vocal ability.

[28] Ken Tucker of Entertainment Weekly considered the track "a tearjerker so grandiose and yet so intrinsically, assuredly hit-bound, it's the kind of mass-appeal grabber that's probably already sent a jealous Diana Ross diving for a comfort gallon of Häagen-Dazs.

"[29] Tucker also named it the worst track on Secrets, and further stated: "Un-Break My Heart" is "one of those the-verses-exist-only-for-the-swelling-chorus showstoppers that allude to emotions without ever actually embodying them.

[35] In Australia, the song peaked at number six,[8] and was later certified platinum by the Australian Recording Industry Association (ARIA), for shipments of more than 70,000 units of the single.

[37] The concept is a melodramatic tearjerker that evolves around Braxton grieving the sudden death of her lover, played by model Tyson Beckford.

She then walks around the house, remembering the happy times she had with him, such as swimming in the pool, having passionate sex with him in the shower, shaving his beard and playing Twister.