Gave Up Too Soon

"[My uncle's] greatest accomplishment was a soft-drink called 4-Up. It wasn't very successful, so he invented 5-Up. Still it didn't click, and then came 6-Up. Still nobody liked it, so he died heartbroken. Little did he know how close he came."

—Victor Borge, Caught in the Act

Timing conspires against the main character(s). As soon as they leave the scene, whatever they were waiting for arrives. Another version of this is having the main character in a zombie attack kill him/herself a few seconds before help arrives.

Frequently occurs when two characters are searching for each other. (In Real Life, the lost are often advised to stay in one place to avoid this trope.)

Frequently only the audience knows it was Real After All.

Needs a Better Description

Compare You Were Trying Too Hard.

Examples:

Anime and Manga

Dirty Pair Flash: Iris (a.k.a. Flare) has a grudge against the 3WA because they didn't provide backup when she called for help, which caused Molly to get killed. Or so she thought -- actually, they could and would have provided backup if she hadn't thrown away her communicator device, assuming that they weren't going to.

Comics

NNY believes that the only reason he can't go through the mirror to a world where everything is better is that he didn't stare at it long enough before touching it. Then he kills someone to take his mind off the issue.
Grant Morrison turns away right before Foxy, his childhood imaginary friend, signals him back from the hills at the end of Animal Man

Film

The main characters in Nick and Norahs Infinite Playlist spend a good chunk of the movie looking for their inebriated friend Caroline. They just lost the cell phone connection with her and decide she's not at the bus terminal, so they leave to look somewhere else. Three seconds later, Caroline emerges from the terminal bathroom.
In Home Alone 2, the mother is looking for her son Kevin all over New York. After searching for him in her brother-in-law's house, she doesn't find anybody so she picks a taxi and leaves, moments before Kevin arrives on the scene.
In the modern adaptation Romeo and Juliet, Juliet starts waking up from her coma as Romeo is drinking his poison, and he realizes his mistake right before dropping dead. This raises the drama from the original, where she merely woke up to find his corpse.
A ridiculously tragic version: in The Mist the main character mercy-kills his son and all his friends (he had just enough bullets for everyone but himself) moments before the ominous pounding sound drawing ever closer is revealed to be the military coming through killing all the monsters and burning up the mist.

Literature

In Neverwhere, Door agreed to meet up with the Marquis at the floating market. They could have touched him, had they known where he was. Dead. By the time he recovered, they had already left.
The book Gold and Silver, Silver and Gold, about buried treasure, mentions that treasure hunters should be persistant because "You could dig four feet down, find nothing, and give up when the treasure is buried five feet down."
- Interestingly, there's a real life instance of this subverted to ridiculous levels. The exact location escapes me, but following a rumor of gold on a island, decades of treasure hunters have dug over a hundred feet down looking for the loot, because "If the previous guy didn't find it, maybe it's just a little bit further!" Considering that the shaft is now so deep to be prone to flooding, and the gold was supposed to be from the 19th century- Chalk this one up to not knowing when to quit, how would the original owners have put gold hundreds of feet down?
  - Do you mean Oak Island?
  - Long story short: Due to the finding man made obstacles, they know something is buried down there but no one has been able to get to it (or, now days, even figure out where the original pit was). Sort story long: Anything by Dickens.

Live Action TV

The Twilight Zone had a rather disturbing example of this trope. In the episode Mr Garrity And The Graves, a con artist scams an entire village into believing he can raise their dead. After being paid not to, he feels badly and performs the phony ritual anyway before leaving town in disgrace. Cue the dead rising.
- The episode "I Shot an Arrow into the Air" involved a space shuttle crashing onto what the astronauts think is a distant desert planet. One Jerkass member of the crew, determined to survive, kills the rest of the crew one by one so he can steal their water canteens. Shortly after killing the captain, the crew member finds out they were on Earth All Along, not far from a freeway leading to Reno, Nevada.
On Seinfeld, the quartet spends the entire episode waiting for their table to be available at a Chinese restaurant. Just after they leave... "Seinfeld, 4?"
In one episode of Doctor Who, Donna Noble lived a highly compressed life in a virtual reality system, meeting "the perfect man", falling in love with him, and having children with him, all in the space of a few real-time minutes. Once she leaves the system, she hangs around to see if he really existed or if he was just a computer illusion. She gives up and leaves, just as he shows up.
The X-Files episode "Quagmire" was about the deaths of several people around a lake where a lake monster is purported to live. The killer turns out to be an alligator that Mulder shoots. Right after he and Scully leave, the lake monster surfaces.
In an episode of Sliders, the characters only have a few seconds to decide whether or not to stay on the latest parallel Earth they've landed on. To see if it's their home or not, Quinn tries a fence, knowing it is always squeaky (something he does in the pilot), and it doesn't squeak. After they leave, a gardener with an oil can comes into view.
Season 2 of Jeremiah; Mr. Smith convinces Jeremiah, Kurdy and Markus that God is going to finally, overtly, come to Earth and grant one wish to each person in a selected place. Each character discusses what their wish would be; Mr. Smith says only to have his broken arm, which the doctor's said had little chance of healing, repaired ("That's it?" * shrug* -"I travel light"). Long story short, they all wander off except Mr. Smith-then the next morning, they are throwing a baseball around, and Mr. Smith catches it-with his theretofore broken arm (saying sadly, "You guys shoulda stayed...").
Happens in the So Weird episode with the aliens, and probably some others as well.

Music

The song "Zangra" by Jacques Brel is about an officer stationed in a frontier fort who looks forward to the enemy attacking so he can become a hero. But years pass and the enemy doesn't come. Finally, he retires, and that's when the enemy shows up.
The song "Stan" by Eminem focuses on the relationship between the artist and an obsessive fan who, furious at his idol for not writing back, kills himself and his pregnant girlfriend. In the final verse of the song, Slim Shady does write a reply encouraging Stan to seek professional help so as not to end up like a suicide victim he heard about on the news and then realizes Stan, himself, was the victim.

Newspaper Comics

Occurs in one week-long Doonesbury story arc. In a pastiche of Waiting for Godot, Mike and Zonker wait for Mario Cuomo to announce his bid for the presidency. The two finally give up out of frustration, and a beat later, Cuomo arrives in the last panel.

Real Life

The Burke and Wills expedition of Australia is a sad example of this. They and their team were to travel from the southern to northern coast of Australia and back. They had left part of the team at a halfway point and took two extra teammates with them to the coast. After waiting for several weeks, the other team gave up waiting and left only nine hours before Burke and Wills returned, which eventually led to their deaths.

Webcomics

After Order of the Stick is forcibly split up, the party mage Vaarsuvius gets fed up with the inaction of the half he/she ended up with and leaves to find a way to reunite with the other half. Once he/she returns with enough power to magically reunite everyone, he/she finds the rest of the party has already gathered somewhere else.
- Perhaps more appropriately to this trope, the Order spends a whole day searching the desert for leads to one of the gates. It's only after they leave that a scry shows up.
  - Though if the scry seems was left by Zz'dtri as the magical aura surrounding it suggests (the character's own spells have auras the same color and style), not exactly a straight usage.

Western Animation

In episode 3F10 of The Simpsons, before normal closing time:

Moe: [sighs] Might as well close the dump.

[outside, Quimby leads a bunch of people toward the bar]

Quimby: I am going to drink you under the table.

Man: No, I am going to drink _you_ under the --

[the "Moe's" lighted sign turns off]

[the crowd sighs and turns back]

- An excruciating example in Treehouse of Horror V's "Time and Punishment" segment.

Homer:[After having changed history via time travel several times] Hmm, fabulous house, well-behaved kids, sisters-in-law dead, luxury sedan...woo hoo! I hit the jackpot. [sits down] Marge, my dear, would you kindly pass me a Doughnut?

Marge: Doughnut? What's a Doughnut ?

Homer: [Shrieks repeatedly and pushes toaster handle, disappears]

Marge: [Looks outside and sees Doughnuts fall from the sky] It's raining again.

In An American Tail, Fievel's parents assume Fievel died while falling overboard on a ship, and they spend most of the movie having near-misses while Fievel is out looking for his family because Papa Mousekewitz refuses to entertain the notion that Fievel is alive.
An American Dad episode involved the Smiths being trapped in a cave. They end up cannibalizing the side character who was with them almost immediately, and are rescued soon after.

Theater

This trope would sum up the ending to Romeo and Juliet quite well.