It appears from here that the BF needs a large mug of Grow The Fuck Up and either come out as gay/bi with his BFF or move into his own space and stop relying on the opinions of his friends to run his life.
In any case, I'll wager that the BF just really isn't available for a relationship with any woman who lives nearby, and that he engages in serial LDRs to keep the women at both a physical and emotional distance. He's got some issues that need to be addressed before he's ready for relationships--hetero or homo, mono or poly.
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.