I trust the civs who are friendly and not coveting my lands.
That.
A few civs are generally more likely to backstab than others, but none of them are programmed to be your best buddy no matter what. If you aren't nearby you can get along, and if you are things will go south. It doesn't matter who the civ is, they're all the same in that regard.
To OP: I've had Oda DoW on me while we were fighting a war with another civ that we agreed on together. Not that this is remarkable because all civs will do that, the point is he's not an exception.