In a single line: AI = Artificial Idiot
In depth:
It's just a computer program. There is a line in the AI files that forces any empire to NOT renew a treaty with you for a certain number of turns after a break, for example. No relation to actual 'attitude' or need for a treaty. Just a hard, arbitrary waiting period. The 'attitude' of the AI works the same way. There is an arbitary 'float' of a certain fraction of a percent per turn. If you are not doing enough damage to make them angry, they get happier.
You can edit the AI files to reduce the enforced waiting period and increase/decrease the 'float' effect. You can also just keep offering a treaty. There is a small positive effect on AI attitude towards for for offering a treaty. Gifts make the AI happier, too.
[ July 07, 2002, 16:40: Message edited by: Baron Munchausen ]