I find good ol' Civ 5 incredibly frustrating in one aspect: attempting to be peaceful and friendly with the computer players. On Warlord difficulty, I was just playing as Siam, and had a long Friendly relationship with Wu Zetian, about 300 turns. I joined in an classical era war, we traded frequently, and made several declarations of friendship. I was aiming for a diplomatic victory, so I hadn't been in a war since Wu and I eliminated Hiawatha from the game. The only negative I had with her was "They believe you are building new cities too aggressively!" I had only built one new city in many, many turns. Then, suddenly, she is denouncing me. It does not make sense to me that she could flip so abruptly from Friendly to Denouncing, followed by Guarded. I guess it's silly to try to be friends with the computer, but this experiences make me want to just conquer everyone first, then decide which victory to get after there's only one weak rival left.