I'm glad it's been usefull to you!

I've had the same problem, I made Makedon an ally, and gave them a lot of provinces, however, they have a BIG problem with me holding Krete. They can't help but attack me every turn or two there, no matter what I give them. I just bribe them a lot, and hope they get over it.

There was an old guide on diplomacy, which is very old now, that suggested you need to offer the AI 2-3k per turn to keep the peace, or improve relations. This is what I do, sometimes it helps, but sometimes the AI gets a real hair in its butt about attacking you again and again. I use cheats for that money, though sometimes I do use my own money for big payoffs, to make it somewhat realistic, or roleplay.

So I just auto_win the constant battles on krete, unless it seems like it's going to be interesting.

And no, you're doing nothing wrong, the AI just sucks sometimes.