I tried a couple of SP games since the patch is out, and i noticed that i don't need the "agressive AI" option anymore... it's almost impossible to get a peacfull game (noble difficulty).
The worst seems to be if you found a religion. I didn't even manage to remain at peace with my brethren in faith (ok, maybe because in the game i'm thinking of they were Japan and Russia with Stalin).
It's nice to see who is who's worst ennemy, but it also seems to have become more important not to interact in any ways with the worst ennemy of your "friends".
Damn it, even AI with the same religion fight eachother and ask me to join their fight (same religion as i am).
Did anyone notice the hormonal imbalance of our digital friends too ?
Yes, it's more or less discussed in this topic:
My conclusion was that most likely it has something to do with your military strenght. As soon an AI sees that a certain civ is weak, they all gang up on that civ.