Gidget
I have friends in all factions that I'd fight for. But I fight for them, not the flag they are under. If you cannot make the distinction, that's your failing.
Same as me, I have friends in all factions. But I don't fight for them, I fight against the flag they are behind. And it's not because we spent 4h fighting each others at SN, we can't make jokes and discuss a lot in PM.
And all of my friends in the game knows the position of my characters. That doesn't mean I don't like them or whatever, my char doesn't like their chars that's about it.
Others example, I can discuss crafting stuff with friends from others faction but I will never craft anything for them and vice-versa.