I started playing a 10 vs all and started getting diplomacy offers, and I went for some. After a while they simply cancel the deal for no apparant reason. Then another faction offers something, and take it back after a while. Tis goes on throughout the game. I was allied with pretty much all of them, just at different times.

What's the point of trying to hold a relationship with the AI if they just keep breaking it for no reason? In my book, an alliance might even last throughout an entire game if we take care of eachother. But that's impossible here. It hardly feels like an alliance at all, because 10 minutes later I'm with someone else again.