The phrase, the eternal triangle, in the title alludes to a romantic relationship between three people, usually two men and a woman or two women and a man. It's first known use is reputed to have been in 1907. Since then, several film shorts and at least one British-made silent film, i.e. The Eternal Triangle (1917), have been made using the phrase as the title. Another, perhaps more erotically suggestive, phrase would be from the French: ménage à trois.