eternal triangle

plural eternal triangles

1. idiomaticA relationship involving three persons (usually two women and one man or two men and one woman) among whom there are conflicting and competing attachments of a romantic or emotional nature.

   And then there’s the eternal triangle thing with Duke fancying Olivia who fancies Sebastian.

   2006 April 6, Margaret Pomeranz, "She's The Man," abc.net (Australia) (retrieved 4 June 2013)

   2 more examples

   "There weren't even any words," she said. "He knocked Loerke down and stunned him, he half strangled me, then he went away." To herself she was saying: "A pretty little sample of the eternal triangle!"

   1920, D. H. Lawrence, chapter 31, in Women in Love

   Wives and Lovers perkily proves that the eternal triangle is still good for laughs. The triangle consists of Author Van Johnson, Wife Janet Leigh and Literary Agent Martha Hyer, who sells Van's novel to a publisher, a book club, a Broadway producer and a movie company. . . . Not content with her 10%, she tries to collect the author too.

   1963 September 6, “Cinema: After the Money Rolled In”, in Time