Meadow Run

"Long separated by cruel fate, the star-crossed lovers raced across the grassy field toward each other like two freight trains, one having left Cleveland at 6:36 p.m. traveling at 55 mph, the other from Topeka at 4:19 p.m. at a speed of 35 mph."

Two lovers run toward each other in slow motion across a meadow filled with flowers and butterflies, arms spread, totally suffused in the joy of their meeting, as Tchaikovsky's Love Theme from the Overture to Romeo and Juliet or Pachelbel's Canon in D (or some other piece deemed romantic) plays on the soundtrack.

Sometimes subverted by interrupting one lover's run violently—sniper rifles are a popular way of doing that—creating Mood Whiplash.

Examples of Meadow Run include:

Anime

Played straight at the end of .hack//SIGN during the ending credits. Not in a meadow, though. Also, the two parties involved are both girls, and one of them is in a wheelchair.
Ifurita and Makoto at the end of El-Hazard: The Magnificent World.
Kurau and Christmas interact lovingly in a sunny meadow during the opening credits of Kurau Phantom Memory, wearing summer dresses—which doesn't appear anywhere in the series itself.
Spoofed in Fullmetal Alchemist in "The Flame Alchemist, the Bachelor Lieutenant and the Mystery of Warehouse Thirteen", where Havoc tries to imagine Major Armstrong's sister, and gets an Imagine Spot of Armstrong in a wig and dress doing a Meadow Run. It turns out that she's actually really hot. She turns him down though.
Played straight with Misa Hayase and Hikaru Ichijo in the episode of Super Dimension Fortress Macross where Earth is glassed. For some reason they forgot to color it.
Tadao Nagahama LOVES this trope. After his Robot Romance Trilogy actually did show romantic premises with Voltes V and Daimos, the ending credits depicts the Reunion Runs accompanied by heartwarming Award Bait Songs (The Gou brothers to their father Dr. Kentaro Gou, Kazuya with Erika.)
Parodied in Soul Eater, although they aren't in a meadow. After a "break up," Soul and Black Star run at each other in slow motion calling each others' names with Love Bubbles in the background.
Renton and Eureka did this in episode 47 of Eureka 7 when they reunite with each other.
An early filler episode of Dragonball Z has villains Vegeta and Nappa land on an alien planet. On a whim they decide to act heroically, killing the tyrannical ruler, and reuniting two lovers. The final scene has the lovers doing a Meadow Run towards each other... then Vegeta blows up the planet.
Similar to the Doctor Who example below, Toriko has the female Battlewolf and her child start running towards each other .....Only for Bui to fire a laser through the mother's body.
A variant here in Billy Bat, with the lovers running to each other from across a train station.

Film

Spoofed in Shrek 2, as the meadow run soon turns into Shrek and Fiona running arm-in-arm from an angry mob.
Also spoofed in Harold and Kumar Go To White Castle, when Kumar engages in a Meadow Run with an anthropomorphized bag of marijuana. And then the bag o' weed and Kumar get married. And fuck.
Also played straight in the movie The Sidehackers (as seen on Mystery Science Theater 3000), set to the film's love theme, "Nothing Lasts Forever" ("Only love/Pads the film").
Appears during a montage of romantic-film-tropes in The Muppet Movie, along with rowing-a-boat and meeting-on-a-foggy-noir-street-corner-in-the-40's.
Used in The Pirate Movie when Mabel first sees Frederic on the beach. Somehow they end up riding horses on the beach moments later.
The trope comes from one of the film versions of Wuthering Heights. "Catherine!" "Heathcliff!" "CATHERINE!" "HEATHCLIFF!"
- Spoofed on Monty Python (see below)
- Spoofed mercilessly on numerous episodes of Dave Allen At Large. But, then, what wasn't?
Appears in Gone with the Wind when Ashley returns to Tara after the war.
Spoofed in Wagons East, in which the heroes are facing death and each imagines his or her loved one in a brief vignette. The last hero is a redneck farmer whose vignette has him performing a Meadow Run with a sheep.
Rama and Sita in Sita Sings the Blues after Rama and the monkey army rescue her. He promptly drops her saying he's redeemed the shame upon his name by rescuing her, but since she lived in the house of another man (the King of Lanka who kidnapped her, but mostly left her alone), she must have slept with the King and is no longer "pure".
Happens four times in Homeward Bound, each time managing to be more heartwarming than the last, mostly because it's kids reuniting with their long-lost pets (or said pets reuniting with each other after one was presumed dead) instead of lovers.
Spoofed in Madagascar as well, where in the middle of Alex and Marty's run, it turns out that Alex is actually pissed off, with it quickly turning into Alex chasing Marty around.
Most Narm-filled moment EVER in New Moon when Aro is seeing Alice's version of the future to prove that Bella will eventually become a vampire. They sparkle as they frolic.
Tony and Maria toward the end of West Side Story. Only, instead of a meadow, it's an outside basketball court. And Tony gets shot, where he ends up Dead in Her Arms Tonight.

Live Action TV

Spoofed in the British TV series Ballykissangel where a man and a woman run towards each other across a grassy meadow. When they meet the woman suddenly punches the man in the face.
~~Awesomely~~ Horrifically twisted in the Doctor Who episode "The Stolen Earth" when the Doctor and Rose run towards each other, meeting for the first time since "Doomsday"... only for a single Dalek to appear in the scene and shoot the Doctor without so much as an "Exterminate". And if that wasn't enough, this leads to a pretty damn big cliffhanger as the Doctor begins to regenerate...
- And don't forget the Doctor and the Master used to run across fields of red grass as kids. And both are prone to reminiscing about this, fondly. Foe Yay party, anyone?
A beautiful, bromantic Meadow Run happens during Season 1 of Chuck, in Chuck Versus the Sandworm between the titular geek and his BFF Morgan.
A rather one-sided Meadow Run (taking place in an office, but still using the slow-mo and romantic music) occured at the end of a 3rd Rock from the Sun episode in which Dick was really happy to see Mary return after she had been gone for a week. Seen here.
Engine Sentai Go-onger spoofed this in one episode when the two female Rangers, Yellow and Silver, do this. Since they were just meeting up to start stage one of their plan to save Yellow's mecha, there was No Hugging, No Kissing, but this didn't stop the blatant imagery from making certain fans Squee regardless.
Happens rather bizarrely in the Tokusatsu Space Sheriff Sharivan, with the run being done by the hero and Jesus.
Parodied in Monty Python's Flying Circus, where this is done by Raymond Luxury-Yacht and a plastic surgeon.
- Not to mention the "Attila the Hun Show" skit.
- "And now, 20th Century Vole is proud to present: The semaphore version of Wuthering Heights!"
Barney Stinson makes a reference to this in an episode, when talking about Robin.

Barney: "I don't love her, okay, I just... miss her when she's not around, I think about her all the time and I imagine us one day running towards each other in slow motion and I'm wearing a brown suede vest."

A non-romantic version in The Color Purple: Celie runs towards her sister Nettie through a meadow after not seeing her for decades.
Happened in The War at Home between Larry and Kenny after their fathers apologized to each other.
Done in The Goodies between Bill Oddie and his new gal. Then done in the same meadow between Graeme Garden and...his computer. He also tries to push it on a swing, which...doesn't work so well.
Spoofed and lampshaded in Kamen Rider Double: In one episode, Shotaro ends up chasing another man along a beach, complete with the slow-mo and the romantic music. As it's happening, Shotaro thinks to himself how strange it must look to someone who doesn't know the context.
Parodied on Bewitched when Mr. and Mrs. Kravitz are reunited after separating.

Newspaper Comics

Parodied in Big Nate, where Nate ran until he got close enough to see that the seeming Love Interest was an old hag. Fortunately, it was All Just a Dream (within a dream).

Video Games

Lucas and Hinawa doing this (sort of, because Hinawa is walking away) is the entirety of Chapter 6 of Mother 3.

Web Original

Spoofed in the Doctor Who fan film "I'm a Time Lord, Get Me Out Of Here!".
At the very end of A Very Potter Musical, Quirrel and Voldemort start to do this, first running towards each other, and then turning around to join back-to-back (it makes sense if you've seen it).
In a Yogscast Minecraft Series special, during Granny_Bacon's funeral, Simon reminisces his time with her, which consists entirely of him and her colliding into each other in a field of wheat and having, presumably, dirty sex.

Western Animation

Spoofed in The Grim Adventures of Billy & Mandy, where lovers Eris and Hoss Delgado run towards each other in a meadow. Hoss is also in a monster truck.
In the Phineas and Ferb episode "It's About Time!", Dr. Doofenshmirtz and Perry The Platypus spoof this, somehow managing to still turn it into Foe Yay. They run toward each other on the beach... and Perry kicks Doofenshmirtz in the face.
Parodied in Tiny Toon Adventures when Buster reunites with his lost dinosaur, and again when Babs and Montana fall in love at the hands of Concord substituting for Cupid.
In the KaBlam! episode, "Won't Stick to Most Dental Work" had a scene where Henry and June were happy to see eachother again after Henry quit, and they ran through a meadow with romantic music playing as they ran up to one another and hugged.
Spoofed in an episode of The Simpsons telling the story of Paul Bunyan. The giant Paul and his normal sized love interest see each other at a distance and run towards each other, but when the love interest realises his true size she turns and starts to run away from him instead.
Parodied in the Beetlejuice series when Lydia and the newly humanoid tree Spooky run to each other.

Truth In Television

The Church of Scientology had a field dug up and planted with flowers for Tom Cruise and new wife Nichole Kidman to romp in.
Isaac Asimov was once invited to an apparently-tedious US/Soviet diplomatic event, without his wife. When it was done, they were to meet outside the venue. Seeing each other at a distance, they simultaneously ran at each other in a Meadow Run. It was, Asimov later found out, caught on film by a Soviet cameraman, and was shown often on Russian TV for a while.