Aida and Radames in both Verdi's opera and the musical Aida. Their lover's duet in the musical is even called "Written in the Stars". In the opera, their tragic lover's duet is known as "O terra addio", which they sing after being buried alive.
Peter and Jason in Bare: A Pop Opera. It is made especially clear these two are a parallel of Romeo and Julietwhen Jason ends his life by downing a lethal dose of GHB.
Billy Bigelow and Julie Jordan from Rodgers and Hammerstein's Carousel, based on the Hungarian play Liliom, which follows the romance of nere'dowell Carousel Barker Billy and his wife former mill worker Julie, and their toxic and abusive marriage. When Billy learns that Julie is pregnant, he vows to become a better provider for his child and wife, even if it means by ways of crime. When caught in the act of burglary, he chooses suicide over facing jail time and dies in Julie arms. Years later, after spending a decade in limbo God, taking pity upon him, sends an angel to guide Billy back to Earth to help his struggling daughter. In doing so, he is granted his place in heaven, but before leaving his spirit lets Julie know just how much he loved her, which she with tears in her eyes seemingly hears.
Dido, Queen of Carthage is a retelling of the star-crossed lovers Dido and Aeneas, from classical mythology.
Brack Weaver and Jennie Parsons in Down in the Valley, with the former already about to be hanged when the action begins In Medias Res.
Bellini also composed I Puritani, which tells the story of Elvira, a Puritan and the daughter of the commander of the fortress at Plymouth, and Arturo Talbot, a Cavalier who supports the Stuart dynasty that was briefly overthrown by the anti-royalist insurgency. However, this story ends happily.
In Knickerbocker Holiday, though Brom and Tina finally get a happy ending by way of narrator ex machina, they spend most of the play separated by the latter's Arranged Marriage and the former's threatened hanging. They also discuss it:
Tina: We'd be figures in story, the legendary lovers of the early Dutch occupation, Brom and Tina, drinking passion and death together in one dark draught! Brom: I'd love to read about it, but that pleasure, unfortunately, would never be mine!
Violetta and Alfredo from Verdi's La Traviata. Violetta, a Parisian courtesan with tuberculosis, falls in love with a Alfredo, a poet, and abandons the world of glamour to live a simple life with him. However, Violetta leaves Alfredo at the request of his father Giorgio, resulting in Alfredo (who knows nothing about this) humiliating her at a party and then being shouted down by Giorgio. Eventually, Violetta's TB worsens, but she and Alfredo manage to reunite before she dies.
Donizetti's Lucia Di Lammermoor has Lucia, the sister of Enrico Ashton, in love with Edgardo di Ravenswood, the rival of her brother. Enrico tries to force Lucia into marrying his ally Arturo after Edgardo leaves for France, but it ultimately culminates in Lucia going mad, murdering Arturo, babbling and singing madly in front of Enrico and others, and then dying of said madness. When Edgardo finds out, he commits suicide out of grief.
Ti Moune and Daniel in Once on This Island which Ti Moune sold her soul to Papa Ge to let Daniel live so she can fall in love with him but Daniel was arranged to marry Andrea which led Ti Moune to die of a broken heart.
Debussy's opera Pelléas et Mélisande tells the story of Mélisande, a young woman married to Prince Golaud, who falls in love with her husband's half-brother Pelléas. Naturally, this results in Golaud using their child to spy on the two lovers, and ends with Pelléas being killed by Golaud and Mélisande dying after giving birth to their daughter.
Roméo et Juliette by Gounod is based on Shakespeare's famous play, so of course it deals with this.
Bellini's earlier opera I Capuleti e i Montecchi also tells the same story. However, in this version, Giulietta (Juliet) is engaged to a man named Tebaldo (Tybalt), who completely replaces Paris, but Giulietta is in love with Romeo, who is the leader of the Montecchi (Montagues). Just like Shakespeare's play, Romeo and Giulietta commit suicide at the end.
Rusalka and the Prince in Dvorak's Rusalka. Because Rusalka is a water spirit and the Prince is a human, they can never really be together, and Rusalka trying to turn into a human doesn't help at all, as the Prince ends up seduced by a Foreign Princess on his wedding day. In the end, Rusalka is condemned to be a demon of death at the bottom of the lake, while the Prince dies after accepting Rusalka's kiss.
In the musical adaptation of The Secret Garden, it is revealed at one point that Lilias Craven's family, especially her sister, were dead set against her marrying Archibald because he was a hunchback. Her sister threatened to disown her, but she married him anyway because she loved him so much. Then she died. Archibald is still in a mess over her death when Mary arrives ten years later.
Floria Tosca and Mario Cavaradossi in Puccini's Tosca. After Cavaradossi is arrested for hiding a political prisoner, the corrupt Scarpia forces Tosca to reveal the prisoner's hiding place by torturing Cavaradossi, which results in her lover's anger and political gloating before he is led to execution. Scarpia then gives Tosca the ultimatum that if she sleeps with him, he'd let her lover go. However, despite Tosca killing Scarpia, it turned out that he lied and Cavaradossi ends up killed, so Tosca also commits suicide to avoid arrest.
Tristan and Isolde in Tristan und Isolde, the opera by Richard Wagner. Tristan escorts Isolde, Princess of Ireland, to Cornwall where she is being forced to marry his uncle, King Marke. Isolde has already fallen in love with Tristan and she compels him to take poison with her because she detests the idea of marrying King Marke. However, her maid, Brangane, prepares a Love Potion instead, causing Tristan and Isolde to start an affair. Tristan's friend, Melot betrays him and exposes the affair to King Marke. Melot and Tristan fight, but, at the crucial moment, Tristan throws his sword aside and allows Melot to stab him. As Isolde arrives at his side, Tristan dies with her name on his lips and she dies too.
In the original Vanities play, the three Childhood Friends are driven apart by their differences in the third scene, although The Musicalfixes that. Played straight with Joanne and Ted, who are divorced by the musical's finale.
Maria and Tony in West Side Story, a musical based on Romeo and Juliet. Tony is a member of the Polish-American street gang The Jets (though he's been trying to leave), Maria is the younger sister of Benardo the leader of the rival Purto Rican immigrant gang The Sharks. In a slight departure from Romeo and Julietonly Tony dies, in a revenge shooting for him killing Bernado (the Tybalt stand in, who killed Tony's best friend Riff who was the equivalent to Mercutio). Maria cradles Tony in her arms as he dies and then delivers a "Reason You Suck" Speech to the rest of the cast.
Elphaba and Glinda from Wicked. It's far more blatant in the musical than in the books, and fits this trope far more than said source. That greatly depends on the staging. It's more like a star-crossed friendship. In the book, Elphie and Fiyero are the star-crossed lovers.
Pelleas and Melisande (French: Pelléas et Mélisande) is a Symbolist play by Maurice Maeterlinck about the forbidden, doomed love of the title characters.
William Shakespeare did this a lot, either because he liked it or his audiences did.
Romeo and Juliet, the Trope Namer, from the opening narration, although according to some interpretations, it's more of a Deconstruction of this trope, with Romeo and Juliet both being shown to be foolishly emotional and needlessly dramatic. It's still made clear the ongoing feud and Juliet's father's insistence on her marrying Paris when she's only thirteen are huge factors in their deaths.
Antony and Cleopatra - Antony is forced to marry his comrade's sister, and his betrayal of that in favor of the Egyptian queen leads to a misunderstanding where he thinks she's died and then kills himself. She likewise suicides in the climax of the play.
Lorenzo and Jessica in a side-plot of The Merchant of Venice. Jessica is Jewish and her father is the play's antagonist, forcing her to flee in the dead of night. They earn their happy ending.
Pyramus and Thisbe, a Show Within a Show in A Midsummer Night's Dream, which has its own forbidden lovers in Hermia and Lysander - she is promised to another by her father's insistence (and refusing him is punishable by death under Athenian law). But since this is a comedy, they end up together.
Hamlet and his lover Ophelia start out in love, but the latter's family already disapprove of the match. As Hamlet loses it during his quest for revenge and kills Ophelia's father, Ophelia herself goes mad and eventually drowns herself.
Othello and Desdemona. The latter disobeys her father's wishes to marry Othello - who is both older than her and a different race. Thanks to some manipulations by Iago, Othello believes Desdemona is cheating on him and strangles her to death.
