Eternal Triangle and Eternity

Love triangle is often called eternal – why? Does it mean that it lasts forever? Its highly prolonged character is possible of course, but that's not the case. It's just that the situations when love affair involves more than two people happen all the time irrespective of any possible extraromantic factors.
Love triangles are beyond time and age, country borders or moral limitations. They interfere with any possible stages and statuses of people's lives: teen age, middle life, sometimes even old age; marriage and loneliness, business and boredom... Love triangles don't care about people's being totally unready for their arrival, they just visit us knock on our door without invitation or even a pre-visit call...
Love triangle is eternally universal. Irrespective of many possible individual variations and slight deviations from the 'norm', its pattern is stably the same: there is one someone who is surrounded by two someones who are after him or her. One of them will be dissed in the long run, another one is the so-called champion. The center 'angle' invariably wallows in doubt but knows that the decision must be made.
All these factors contribute to the situation with love triangle becoming a stable eternal pattern which visits people's lives irrespective of the year or the century they live in, their status or income, their character or outlook.