What does theatre tell us about love, asks Peter Crawley

It’s almost Valentine’s Day, a time for love, romance and heart-shaped marketing opportunities, when everyone looks for a movie to make the pulse quicken. It generally has a plot as warmly formulaic as it is inflexibly heteronormative: Boy meets girl. Boy loses girl. Boy gets girl back again. The end.

But if you’re looking for a “date play”, dream on. Take a classic love story, such as Romeo and Juliet, and see how it messes with the plan: Boy meets underage girl. Boy loses girl after marrying her in secret and killing her cousin. Boy gets girl back again, only girl appears to be dead, so boy kills himself, but actually girl is not quite dead, then wakes up and finishes the job. The end.

The course of true love has never run smooth, but most plays make it seem so rough you wonder why anyone ever bothers. Calipo's recent 10 Dates with Mad Marywas an honourable exception. But anyone hoping to see a romcom onstage will have to wait. After the forthcoming Les Liaisons Dangereusesand Sodome, My Love, there's the looming stage version of When Harry Met Sally. Now, they may all contain orgasm scenes, but you can guess which one has a happy ending.

Until then, here’s a spoilers- filled lovers’ guide to some current shows, each one a cold shower for any enflamed heart.

• Off Plan (Project Arts Centre): Boy meets girl. Boy sacrifices daughter of girl to the Gods. Girl meets another boy and they take revenge on first boy. Girl's remaining children – let's call them boy and girl – reunite to avenge their father's murder. Boy put on trial by the gods. Boy beats the rap.

• Christ Deliver Us! (Abbey): Boy knows girl in the Biblical sense. Girl doesn't know much at all about the Biblical sense. Boy explains various Biblical senses to another boy. Another boy commits suicide. Girl dies after botched abortion. Boy sent down. Bible gets away.

• Haunted (Gaiety and Grand Opera House): Superannuated boy meets much younger girl. Superannuated boy gives much younger girl various gifts that once belonged to his dead wife. Wife not quite dead, actually. Wife is understandably miffed. Superannuated boy doesn't know what's hit him.

• Faith Healer (Gate): Boy meets us. Boy tells us story. We meet girl. Girl tells us slightly different version of boy's story. We meet their agent. He's a hoot. Boy meets us again. Boy loses us.

• Little Gem (Peacock): We meet girl. We meet mother. We meet grandmother. Boys are discussed. Girl gets knocked up. Boy scarpers. Mother lost boy long ago, but meets a hairy prospect. Grandmother's boy suffers stroke, Grandmother meets battery-operated alternative.

• Hamlet (Town Hall Theatre, Galway): Boy meets ghost. Ghost asks for revenge. Boy rejects girl. Boy develops unsettling fascination with mother. Boy kills girl's dad. Girl goes quite mad, sings Hey non nonny nonny. Everybody loses everybody else.