Duets are a brilliant way to show the relationship between two people; they may be in love, or just discovering a beautiful relationship, or they may be in the middle of a bitter argument...IN SONG! So what better way of showing the loss or break-up of the couple than by singing a duet alone? It works like this; Alice and Bob have rehearsed a duet, but Bob doesn't show. What does Alice do? Sing her half only. In the worse case scenario it's not even a duet and Alice was originally only to be doing the backing vocals. Not to Be Confused with Solo Duet, which is where somebody sings a duet alone, or Distant Duet, where both parts are sung "alone", but cut together.
- Tenacious D in The Pick of Destiny: Heterosexual Life-Partners JB and KG split up because they've been invited to a sorority house party: KG wants to go, JB feels they should concentrate on their Quest to find the eponymous pick. At the party KG's talked into playing some of the songs he & JB have written, but he only knows the words for his parts (which are backup to JB). This doesn't go over well.
across the devil's plainand his crossclimbed K2, even stopped a moving trainto
- Elf - Jovie starts off singing an Unduet of "Baby, It's Cold Outside" in a Shower Scene. Buddy joins in, softly at first, ever slowly increasing in volume until Hilarity Ensues.
- This gets played with, at the very least, in Enchanted. After the prince finally finds Gisele again, he starts singing the duet from the start of he movie. However, when it comes to Gisele's part, there's silence. The prince even points out, "You're not singing." This is plot relevant, as it reveals that Gisele is no longer in love with him and has also been grounded by reality.
- The Richard Pryor Show: and the Pips perform "Grapevine" and "Midnight Train to Georgia" without Gladys Knight.
- There's an episode of Clarissa Explains It All where Clarissa wants to perform a duet, but her duet partner can't make it. She performs one half of the duet in front of Sam and he tells her she looks like she's waiting for a bus when she's not performing.
- An episode of Blue's Clues uses this, having Steve sing half of a duet and "you" the viewer are supposed to sing the other half.
- Taken to an extreme in Malcolm in the Middle - Hal is in a Barbershop group, but his son Dewey points out all he does is dance around in the back and offer the occasional backing vocal. Dewey goes on to throw the Apple of Discord around the whole group, until they're so furious with each other they refuse to perform... so Hal gets on stage and dances around in near-complete silence doing his part of the act, until the rest of them join in out of pity.
- In the documentary Young@Heart, about a nursing home singing group who specializes in covering pop music, a duet of Coldplay's "Fix You" is planned between two of the of veterans of the group, but following the death of one of them it has to be done as a solo.
- Non-musical version in The Golden Girls. The three ladies are rehearsing a tap dance routine for a charity event, and Dorothy injures her foot. They continue to rehearse, with long awkward pauses where Dorothy's solo is supposed to be.
- In How I Met Your Mother, Sickeningly Sweethearts Marshall and Lily have a full dance-routine to go with "Don't Go Breakin' My Heart." Marshall, eager to fit in with his new co-workers, doesn't sing the song at karaoke. However, when he decides Lily's more important, he gets on stage and sings his half of the song, until Lily joins in halfway through.
- "What Would We Do Without You?" from Stephen Sondheim's Company: Everyone in the cast has a tap partner to do a Call and Response move with except Bobby—who does his move, then there's no one to follow him. Only a very brief moment in the song.
- In "I Can't Do It Alone" from Chicago, Velma Kelly describes her act with her sister — which can't be done anymore because her sister is dead. Instead of only doing her half, Velma goes "I'd go —" and does her part, then goes "She'd go —" and does her sister's part.
- On YouTube you'll find multiple videos that people have made of themselves singing one part of a duet to the instrumentals of that song, though these are made with the intention of the viewer singing the other part along with the video recording.
- The Simpsons: Homer & Marge are planning to sing "Let's Call the Whole Thing Off" at Marge's cousn's wedding reception but for plot relevant reasons Homer doesn't show up, so Marge just sings her half.
You say potato...You say tomato...Potato...Tomato...Let's call the whole thing off
- In episode 13 of Princess Tutu, the titular Princess Tutu dances a pas de deux (that is, a ballet intended for two people) by herself because the Prince she loves has been brainwashed by the Evil Princess and she is hoping to get through to him via the emotion in the dance.