Yeah.
A "You can't be my friend, if you're their friend too" option.
Very schoolyard, in fact.
Actually, I wholeheartedly agree. It'd stop some of the madness I've seen in one of my games. I was allied with the Yor, but with poor relations with the drengin, and the Yor had allied with the drengin. I had been alied with the Yor for ages (and I must say, they loved me). I declared war on the drengin, and the damn fool yor broke the alliance with me to help the drengin and not me. Sigh.... I suppose it was my fault,for selling them the alliance tech in the first place though!
BTW that was a much more previous version of the game.
~SDC~