First, let's take a look at the diplomatic modifiers which can improve your relationship:
-We have a DoF
-We have a DoF with the same people
-We denounced the same people
-You freed their captured citizens
Now, the negative modifiers
-They covet land of yours
-They covet wonders you built
-You're expanding to agressively
-You denounced them
-They denounced you
-You refused a request after making a DoF
-Your friends found reason to denounce you
-You denounced a friend
-You demanded the not settle near you
-You broke a promise to not settle near them
-You're a warmonger
And I'm sure there are more. Now, what do we need to fix the AI? Simply more positive modifiers, i.e.
-We're at war with the same person
-You agreed to a request after a DoF was made
-We have good trade deals
-You were merciful
And some more couldn't go amiss.
-We have a DoF
-We have a DoF with the same people
-We denounced the same people
-You freed their captured citizens
Now, the negative modifiers
-They covet land of yours
-They covet wonders you built
-You're expanding to agressively
-You denounced them
-They denounced you
-You refused a request after making a DoF
-Your friends found reason to denounce you
-You denounced a friend
-You demanded the not settle near you
-You broke a promise to not settle near them
-You're a warmonger
And I'm sure there are more. Now, what do we need to fix the AI? Simply more positive modifiers, i.e.
-We're at war with the same person
-You agreed to a request after a DoF was made
-We have good trade deals
-You were merciful
And some more couldn't go amiss.
What gives!? Hahaha seems to me that this whole DoF thing isn't working as intended. To me it just seems like another "Pact of Secrecy" mechanism the AI doesn't seem to put much thought into, only use as a pretext to war.