I'm not sure I completely understand your post. But my take on it, and how it relates to me is this: how do I create open relationships ? can I do so on a dating site?
It seems to me that an "relationship site" caters to just that, relationships - people who want to be in a committed long term relationship . That is a category I am not part of.

For me monogamy don't work and I am interested in exploring open relationships, but I'm having some difficulty finding like minded people.