It's not a question of sides. In some deals, things just don't go well, and it's nobody's fault. It's the judging of people and looking for sides that makes this fall down.
I've chatted with both parties in this conflict by PM (all before this incident, nothing to do with this deal) and both people struck me as decent reasonable people. I can't take sides, but I can try to calm tempers, as no matter what happens, one or more of my virtual-friends gets upset.