It's a bitter scene. Alice is at a train station with her beloved Bob, who is about to leave for the war where he may very well be killed. Though sad to say goodbye, Bob insists that he will see Alice again one day, even if it's not in this life. This is one way this trope can play out. The basis is that a character is about to be parted from their loved one (usually significant other) with little hope of reunion, but nonetheless vows to be reunited with them one day, despite how unlikely it may seem.
Sub-trope to Heroic Vow. Compare Never Say Goodbye, I Shall Return, I Will Find You, and I Will Wait for You. Not to be confused with We Will Meet Again, in which a villain swears to fight the hero again as he's being carried off. May be used as a Sequel Hook.
- A commercial for Capital One shows a pair of teenagers saying goodbye at a lake. They vow to meet up again and the boy promises to use his miles card. Cut to them reuniting...in their forties. The girl shoves him into the lake and criticizes him for not getting his miles card from Capital One.
- In Hunter × Hunter, after saving Killua from his evil family, Gon, Killua, Kurapika, and Leorio go their separate ways, but vow to meet up one year later in Yorknew City.
- Magical Girl Lyrical Nanoha ends with Nanoha and Fate promising to meet again once Fate's trial is concluded. Once they actually are reunited at the beginning of the following season, they're basically attached at the hip.
- Love Affair and its remake An Affair to Remember are about two people who meet on a vacation and fall in love, despite being engaged to other people. They agree to meet again in six months at the top of the Empire State Building if their feelings are still strong, but if only one person remembers to, they'll know that the romance was never meant to be.
- In the film Pan, Peter's mother leaves him a letter before leaving him on the steps of an orphanage in which she vows that she will see him again "in this world or another". However, she is revealed to have been killed before a possible reunion, and the failure of the film further extinguishes any possibility.
- The Phantom Menace: Shmi Skywalker promises her son Anakin that they will meet again before he leaves for Jedi training. They do meet again ten years later in Attack of the Clones. Unfortunately, it's during Shmi's dying moments.
- On The 100, "May we meet again" is an excerpt from the traditional funeral rites of the Ark. Characters occasionally use it as a farewell when they are unsure that they will reunite.
- In Once Upon a Time, "I will always find you" is considered something of a family motto to Snow White and David, mostly because there is always someone trying to barge into their lives and undo their Happily Ever After.
- Thomas Dolby's song Europa And The Pirate Twins begins with Dolby and Europa as children playing pirates, until war separated them. "We swore a vow that day / We'll be the Pirate Twins again, Europa." Years later, Dolby is an unremarkable nebbish living Oop North, while Europa tours the United Kingdom as a celebrity. Europa's bodyguards make sure Dolby gets nowhere near the gorgeous kitten.
- The Vera Lynn song "We'll Meet Again" is about the singer promising to meet her loved one again one day.
- Tales of Arcadia:
- At the end of the final season of Trollhunters, Jim, Claire, and Blinky depart to set up a new Trollmarket around a Heartstone in New Jersey, insisting that Toby must stay behind to protect Arcadia. As they're saying goodbye, Jim promises him that they will be back someday, to which he tearfully responds, "You better!"
- In 3Below, Krel is forced to activate the device causing the "Groundhog Day" Loop to avoid discovery by authorities, thus making it so he and Aja never met Jim and his friends and erasing their memories. However, Blinky confidently states that fate will reunite all of them. This is proven true by the fact that they already did meet in Trollhunters in the Backdoor Pilot.
- In the seventh season of Voltron: Legendary Defender, Krolia, about to be parted from Keith again, apologizes for having to say goodbye to him. However, Keith insists that it isn't goodbye. He bequeaths his knife to her and tells her she can return it "when [they] see each other again". Sure enough, in the season finale Keith wakes up in a hospital bed to see her and Kolivan there, having made their way to Earth.