[thejeff]

There is a difference between being completely untrustworthy where NAPs and other deals have no meaning whatsoever and breaking a pact to avoid losing the game.

Would I trust someone less who did this? Yes. Especially when I started to get too powerful.

Would I never trust them again? No. I have no reason to believe he'd break a deal under normal circumstances. Breaking a deal to keep someone from winning is different than breaking one just to grab some of their land (or whatever.) And he didn't sneak attack, but gave 3 turns of warning.

Personally, I suspect the main lesson is to avoid long-term pacts like this one. The game can change too much, too quickly. I have made deals for peace until a particular enemy is beaten, but that's much more situational.