History LoveTriangle / Theatre

** A minor but key piece of the plot in ''Theatre/RomeoAndJuliet''; another man, Paris, wants to marry Juliet, who can't admit publicly that she and Romeo are a couple due to the feud between their families. This leads to Juliet's decision to [[FakingTheDead fake her own death]], as she can't see any other way out of the marriage.

** ''Theatre/RomeoAndJuliet'': Juliet is [[ArrangedMarriage promised to]] Count Paris, but falls in love with Romeo and secretly marries him. FinaglesLaw promptly ensues and both Romeo and Juliet end up dead.

* Creator/ClaudeDebussy's ''Theatre/PelleasEtMElisande'', where Pelléas is up against his half-brother Golaud for Mélisande, who is married to Golaud but loves Pelléas.

* ''Theatre/RomeoEtJulietteDeLaHaineALAmour'', a musical adaptation of ''Theatre/RomeoAndJuliet'' takes the classic love triangle of Romeo, Juliet, and Count Paris and adds the twist that ''[[KissingCousins Tybalt]]'' is also in love with Juliet.

* In ''Theatre/ThePhantomOfTheOpera'', the Phantom loves Christine, who's in love with Raoul.
* The relationship between Eliza, Professor Higgins and Freddy in ''Theatre/MyFairLady'' is considered this.
* Elisabeth of ''Theatre/{{Elisabeth}}'' is the center of a love triangle with her husband the Emperor Franz Joseph and with Death himself, though her husband does not even know that der Tod exists. Death, however, is fully aware of the situation:

** He tells Elisabeth at her wedding that she will regret the choice she has made because she loves him and not Franz Joseph, and he is right, despite Joseph's unconditional love for Elisabeth no matter how far she pulls away.
* Many of [[Creator/WilliamShakespeare Shakespeare's]] plays include love triangles:
** ''Theatre/AMidsummerNightsDream'' has ''multiple'' love triangles among the same group, due to Oberon and Puck's interference. Initially, Hermia and Lysander love each other, Demetrius also loves Hermia[[note]]which wouldn't be a problem for Hermia and Lysander except that Hermia's father prefers Demetrius, and he has the authority to make the choice for her[[/note]] and Helena loves Demetrius, who couldn't care less about her. Seeing this, Oberon orders Puck to use a love potion on Demetrius to make him fall for Helena, but Puck gets Lysander by mistake, causing ''Lysander'' to fall for Helena. They ultimately straighten it out and manage to put things as they originally intended -- Hermia and Lysander back together, and Demetrius in love with Helena.
** In ''Theatre/AllsWellThatEndsWell'', the protagonist, Helena, a countess' ward, falls in love with a high-status man who won't give her the time of day. She secures his hand in marriage with the help of the King, but can't make him love her and he runs off to Italy where he becomes infatuated with another woman, Diana. Diana and Helena end up conspiring (with a large helping of ValuesDissonance) to get Helena's husband to fall for her.
** A minor but key piece of the plot in ''Theatre/RomeoAndJuliet''; another man, Paris, wants to marry Juliet, who can't admit publicly that she and Romeo are a couple due to the feud between their families. This leads to Juliet's decision to [[FakingTheDead fake her own death]], as she can't see any other way out of the marriage.
** ''Theatre/TwelfthNight'' has a perfect triangle version by way of cross-dressing. Viola, [[SweetPollyOliver disguised as a boy]] and using the name Cesario, takes a position in the service of Duke Orsino, only to end up falling for him. Orsino, meanwhile, is pursuing a beautiful but reclusive countess named Olivia, and sends "Cesario" to deliver a profession of love by proxy, which Viola does so well that Olivia is swayed and falls in love -- with "Cesario". It's {{Lampshade|Hanging}}d by Viola in a famous monologue from the play.
--->'''Viola:''' How will this fadge? My master loves her dearly. And I, poor monster, fond as much on him. And she, mistaken, seems to dote on ''me''.
** Subverted in ''Theatre/{{Othello}}''. As part of a plan to drive a wedge between Othello and Cassio, Iago convinces Othello that Desdemona and Cassio are having an affair, but not only are they not actually involved in any kind of relationship, they don't even have feelings for each other.
* In the musical ''Theatre/{{Violet}}'', the title character is in one with with Monty and Flick.

* In Verdi's ''[[Theatre/AidaVerdi Aida]]'', Princess Amneris of Egypt loves the warrior Radamès, but he's in love with her Ethiopian slave Aïda.
** The [[Theatre/AidaJohnRice musical adaptation]] ultimately contains the same triangle, but unlike the opera, it doesn't fully form until near the end of the first act (the opera begins with Radames and Aida already a couple).
* Nadir and Zurga both share feelings for the priestess Leïla in Bizet's ''Theatre/{{The Pearl Fishers}}''. Ironic, since earlier, they sang the famous duet 'Au fond de temple saint' in which they swear that their friendship wouldn't be ruined over Leïla.
* In Donizetti's ''Roberto Devereux'', Queen Elisabetta (Elizabeth) is in love with Roberto Devereux (Robert Devereux), who's in love with Sara, the Duchess of Nottingham. Naturally, this ends in tragedy.

* Meyerbeer's ''L'Africaine'' has this between African slave girl Sélika and Admiral Don Diego's daughter Inès for naval officer Vasco de Gama.

* Bizet's ''Theatre/{{Carmen}}'' two love triangles: one with sweet village girl Micaela against FemmeFatale Carmen for soldier Don José; the second one being Don José against bad boy toreador Escamillo for Carmen. The latter is perhaps the deadliest love triangle in the entire opera.
* Ponchielli's ''La Gioconda'' actually subverts this. At first, Gioconda seems to be competing against Genoese lady Laura for the affections of Prince Enzo Grimaldo. However, Gioconda's love for her mother prevails, as after finding out that Laura saves her mother's life, Gioconda puts aside her own feelings for him to repay Laura and helps both Laura and Enzo escape before sacrificing herself.

* Wagner's ''Tristan und Isolde'' has one between Tristan and King Marke of Cornwall for Irish princess Isolde.
* ''Cavalliera Rusticana'', dear God. Turiddu, a soldier, has an affair with Santuzza, a village girl, to get revenge on a married woman named Lola; however, Santuzza loves Turiddu. Lola is driven with jealousy so she and Turiddu both mock Santuzza and scorn her, and Santuzza ends up telling Lola's husband Alfio of the affair, who then challenges Turiddu to a duel, in which he is killed.
* Verdi's ''Theatre/{{Il trovatore}}'' has a one-sided love triangle, with the corrupt Count di Luna against the troubadour Manrico for the affections of Leonora, who is in love with Manrico.
* There's also Debussy's ''Pelléas et Mélisande'', where Pelléas is up against his half-brother Golaud for Mélisande, who is married to Golaud but loves Pelléas.
* Rossini's ''Theatre/{{The Barber of Seville}}'' has Count Almaviva and Doctor Bartolo competing for the affections of Rosina, who loves Almaviva. This is one of the few love triangles with a happy ending for all.
* The Czech opera ''The Bartered Bride'' by Smetana has a love triangle between Jenik and Vasek for village girl Marenka.
* Another Rossini opera, ''La donna del lago'', has a love triangle between rebel chieftain Malcom Groeme and Uberto di Snowdon for Elena, the Lady of the Lake.
* The love triangle in Janacek's ''Jenufa'' is between Laca and Steva for the titular heroine.
* Donizetti's ''L'elisir d'amore'' has one between simple peasant Nemorino and sergeant Belcore for the wealthy Adina. However, unlike most of these examples, it ends well.
* There's Mozart's ''Le nozze di Figaro'', with a love triangle between Count Almaviva and Figaro for Figaro's own fiancée Susanna.
* ''La favorita'' by Donizetti has Leonora di Guzman caught in a love triangle between Alfonso XI, King of Castile, and her lover Fernando.
* Yet another Rossini opera, ''Il turco in Italia'', has Fiorilla, the unfaithful wife of Neapolitan Don Geronio, caught in a love triangle between Prince Selim and Narciso. There's also a love triangle between Fiorilla and Turkish woman Zaida for Prince Selim. And if that weren't enough, there's another love triangle between Geronio and Prince Selim for Fiorilla.
* In Strauss' ''Der Rosenkavalier'', there is a love triangle between Marschallin Princess Marie Thérèse von Werdenberg and Sophie von Faninal for Octavian, Count Rofrano.
* Cilea's opera ''Adriana Lecouvreur'' has a love triangle between the French actress Adriana Lecouvreur and the Princess de Bouillon for Maurizio, the Count of Saxony.
* Love triangles are common in plays by Creator/FedericoGarciaLorca. Curianito, his fiancée and Butterfly in ''Butterfly's Evil Spell''; Belisa, Perlimplín and [[spoiler:Perlimplín in disguise]] in ''The Love of Don Perlimplín''; Yerma, Juan and Victor in ''Yerma'' (though Yerma and Victor’s relationship are more like the romance that could, and perhaps should, have been). When his plays don’t have a love triangle, they often have a LoveDodecahedron instead.
* ''Theatre/LaSylphide'' has two love triangles. The first is between a young man named James, his fiancee Effie, and the titular [[OurFairiesAreDifferent Sylphide.]] The second is between James, Effie, and another young man named Gurn.

* A one-sided love triangle appears in Puccini's ''Theatre/{{Tosca}}'', with good-hearted painter Mario Cavaradossi competing against corrupt Baron Scarpia for singer Floria Tosca. Though, calling it a love triangle would be a stretch, seeing as Scarpia doesn't really love Tosca and wants to rape her. Even Tosca hates Scarpia for endangering her lover Mario.

** ''Theatre/TwelfthNight'' has a perfect love triangle by way of cross-dressing. Viola, disguised as a boy and using the name Cesario, takes a position in the service of Duke Orsino, only to end up falling for him. Orsino, meanwhile, is pursuing a beautiful but reclusive countess named Olivia, and sends "Cesario" to deliver a profession of love by proxy, which Viola does so well that Olivia is swayed and falls in love -- with "Cesario". It's {{Lampshade|Hanging}}d by Viola in a famous monologue from the play.

** Subverted in ''Theatre/{{Othello}}''. As part of a plan to drive a wedge between Othello and Cassio, Iago convinces Othello that Desdemona and Cassio are [[YourCheatingHeart having an affair]], but not only are they not actually involved in any kind of relationship, they don't even have feelings for each other.

** ''Theatre/AMidsummerNightsDream has ''multiple'' love triangles among the same group, due to Oberon and Puck's interference. Initially, Hermia and Lysander love each other, Demetrius also loves Hermia[[note]]which wouldn't be a problem for Hermia and Lysander except that Hermia's father prefers Demetrius, and he has the authority to make the choice for her[[/note]] and Helena loves Demetrius, who couldn't care less about her. Seeing this, Oberon orders Puck to use a love potion on Demetrius to make him fall for Helena, but Puck gets Lysander by mistake, causing ''Lysander'' to fall for Helena. They ultimately straighten it out and manage to put things as they originally intended -- Hermia and Lysander back together, and Demetrius in love with Helena.

** ''Theatre/TwelfthNight'' has a perfect love triangle by way of cross-dressing. Viola, disguised as a boy and using the name Cesario, takes a position in the service of Duke Orsino, only to end up falling for him. Orsino, meanwhile, is pursuing a beautiful but reclusive countess named Olivia, and sends "Cesario" to deliver a profession of love by proxy, which Viola does so well that Olivia falls in love -- with "Cesario". It's {{Lampshade|Hanging}}d by Viola in a famous monologue from the play.

-->'''Viola:''' How will this fadge? My master loves her dearly. And I, poor monster, fond as much on him. And she, mistaken, seems to dote on ''me''.
** Subverted in Theatre/{{Othello}}. As part of a plan to drive a wedge between Othello and Cassio, Iago convinces Othello that Desdemona and Cassio are [[YourCheatingHeart having an affair]], but not only are they not actually involved in any kind of relationship, they don't even have feelings for each other.

* Many of [[Creator/WilliamShakespeare Shakespeare's]] plays include love triangles, e.g.:\\
''Theatre/AMidsummerNightsDream\\
Theatre/AllsWellThatEndsWell\\
Theatre/{{Othello}}\\
Theatre/RomeoAndJuliet\\
Theatre/TwelfthNight''