Is keeping friendly modifiers completely useless?

[Shifted]

I just don't understand why these two AIs would declare war on me. One of them was my friend, the other only had positive modifiers.

Anyone have any idea? I played that turn again and again trying to figure out what I could do different, the only thing that prevented Gilgamesh from declaring war on me that turn was if I didn't declare friendship with him, which makes no sense whatsoever. Brazil declares war no matter what.

 

[GoodSarmatian]

I think the issue here is with Gilgamesh. He seems to be the one leader who can make any other AI attack you,

 

[Zenstrive]

the AIs agenda seems to be being followed religiously by the AI.
I have been friends with Vicky for 200+ turns, but once I built my second city on another continent (not hers), he declared war on me.
Thanks God we're separated by very long mountain range (what's up with that? My civ and Peter's are boxed by this mountain range and sea