It's your loss because you care about being seen as Good Man with Morals, Principals, and Please Pat My Head.
If you want the fighting to cease, and you're well aware of the mood on both sides-force a summit between the head of both parties. Neither wants a war to for the next hundred years, not even the party that is destined to win if there's no interference.
Or, and this works just as well, LEAVE. STOP ANSWERING THE DOOR. LEARN TO SAY NO. CEASE INVOLVING YOURSELF IN OTHER PEOPLE'S PROBLEMS.
You don't have the balls or will to conquer the world, than stop fiddling with it.