Basic Trope: A long-time friend wants to upgrade the relationship to romance, but the other friend doesn't reciprocate.

• Straight: Alice has been friends with Bob since elementary school, but when she returns from a trip abroad to become his girlfriend, she finds that he's hooked up with Carol instead.
• Exaggerated: Bob made a Childhood Marriage Promise to Alice, and she shows up in full bridal regalia, ready for the scheduled wedding, only to learn that he's now in love with Ted.
• Downplayed: Alice was classmates with Bob in junior high, but although she had a bit of a crush on him, Bob has never been more than a warm acquaintance to her.
• Justified:
  • Bob was more affected by the Westermarck Effect than Alice, and thinks of them Like Brother and Sister.
  • Or Bob is gay, and Alice never knew it.
• Inverted:
  • Victorious Childhood Friend.
  • First Girl Wins
• Subverted: As soon as Alice reminds Bob of the Childhood Marriage Promise, he dumps Carol.
• Double Subverted: But then Bob weasels out of his promise as quickly as possible, because he now fancies Dorothy.
• Parodied: Alice, childhood friend of Bob, shows up to romance him...only to discover that "he" was actually a girl all along.
• Zig Zagged: Alice shows up, only to find Bob hooked up with Carol. But Bob dumps Carol for Alice because of the Childhood Marriage Promise, only to weasel out of the promise to date Dorothy, but he's still giving Alice mixed signals....
• Averted: Any childhood friends that show up just want to be friends like before.
• Enforced: "We need a romantic rival to cause problems for the Official Couple and keep some conflict going. How about Bob's childhood Alice shows up, and she's still carrying a torch for him?"
• Lampshaded: "You...didn't fall for someone else while I was away, did you, Bob? After all, I was here first".
• Invoked: "Bob, you're acting like you don't even know me. I just want to talk to you, It's not like I want to marry you".
• Exploited: ???
• Defied: "Fall in love with Bob? We were just kids!"
• Discussed: "Yes, Carol, Alice does seem to have a crush on me, but we're Like Brother and Sister, no need for jealousy there".
• Conversed: "So, this new character on Generic Romantic Comedy, Alice. Unlucky Childhood Friend or Victorious Childhood Friend?"
• Deconstructed: Alice has let a childhood infatuation run her life for years, robbing herself of the chance to establish healthy romantic relationships with people who might return her affections.
• Reconstructed: Bob helps Alice to overcome that infatuation. They both enter healthy relationships at various times, but end up falling for each other.
• Played For Laughs: Alice is a Clingy Jealous Girl who always assumed they'd get together, while Bob is unaware of her feelings. Hilarity Ensues.
• Played For Drama: Alice is willing to do ANYTHING to ensure they stay together. Bob isn't aware she views him with such obsessive devotion.

Basic Trope: Childhood friends end up in a romantic relationship together.

• Straight: Bob ends up with Alice, who knew him since they were children.
• Exaggerated: They were born on the same day, in the same hospital, and owing to a shortage of cribs ended up in the same one.
• Downplayed: Bob's known Alice for quite a while, but they've never been close until suddenly he notices She Is All Grown Up.
• Justified: Alice is the girl that knows Bob the best (and vice versa).
• Inverted:
  • Unlucky Childhood Friend
  • Last Girl Wins
• Subverted: Alice and Bob get together, but later break up.
• Double Subverted: ...And later get back together again.
• Parodied: Bob partakes in a polyamorous relation with a whole harem of childhood friends.
• Zig Zagged: Alice and Bob break up and get back together several times.
• Averted:
  • Bob knew none of his Love Interests from his childhood.
  • Any childhood friends are Platonic Life Partners.
• Enforced: The writer had Alice and Bob know each other from childhood to reinforce their status as the Official Couple.
• Lampshaded: "Childhood friends do oftentimes end up together in fiction, so it's not strange that you'd think that way about your own, Bob".
• Invoked:
  • Upon considering possible mates, Bob immediately decides upon and pursues his childhood friend, thinking that since they know each other so well, their relationship will likely be stable.
  • Alternately, Alice and Bob are bound in an Arranged Marriage.
• Exploited: ???
• Defied: Bob makes sure Alice knows that they are Like Brother and Sister to avoid romantic complications that could ruin their friendship.
• Discussed: "While you're considering different girls, Bob, what do you think of Alice? I mean, she's pretty much always been with you".
• Conversed: "Oh, so Alice is Bob's childhood friend? Yeah, there's a good chance they'll end up together".
• Deconstructed:
  • Because Alice and Bob had seen each other Like Brother and Sister previously, their newfound relationship feels extremely awkward, almost as if it was Brother-Sister Incest.
  • Bob marries with Alice because he feels he knows her well, as they are Childhood Friends. He realizes that friends don't always make good spouses, and has to deal with this.
• Reconstructed: Alice and Bob manage their way through the awkwardness and settle into a very stable relationship.