And, if I were, I'd likely offer the rejoinder that they'll probably eventually develop the capacity for true loving relationships when they meet "the Other One." Just wait and see.
When speaking of various forms of non-monogamy...it ain't poly if you're just fucking around.
While polyamory, open relationships, and swinging are all distinctly different approaches to non-monogamy, they are not mutually exlusive. Folks can, and some do, engage in more than one of them at a time--and it's all good.