I was playing Sins tonight, trying to become friends with the Vasari west of my Empire. I had just completed a couple of missions for them, taking out the Advent players to the East, and was hoping to draw out them into a cease fire.
But then, all of a sudden, I start getting notifications that the Vasari player was dropping our trade treaties. I skip over to the diplomacy screen and see that our relations had reset to 0%, even though not a minute before I had completed a mission for him and gotten up to 60% relations.
Now, this I was playing against 3 hard AI's for the first time; is this a normal side effect of playing against hard AI's, that they become psychotic backstabbers? Or is there a bug in the diplomacy system?