I know by my own experience that it really exists, and can last even for many years, but if only two people REALLY don't think of each other like men and women. If they just like each other's company and s.o.
By the way, it is very useful to have a real friend- of man sex. A woman can ask him any questions and advice that women don't know.
But if THERE IS s not only friendly sympathy between them, the friendship lasts till some of the two has enough courage to say about feelings and they begin to be not only friends ;))) But that's good too- a good relationship is when it starts from friendship