It could be an interesting feature if combined with treaties. Make it so that all diplomatic relations, excluding war/hatred, require the signing of a treaty and the treaty has a set amount of time until expiration. To pick an arbitrary number out of thin air, a 6 month limit. When a treaty is being signed the choices will be something like, 4 weeks, 6 weeks, 8 weeks, 10 weeks, 12 weeks, etc to 24 weeks.
I'm not sure how I feel about the idea in general, I'm getting rather annoyed with how the game is increasingly trying to force people to play a certain way (what's the next step, handing players a script to play out?).
But this variation of the idea feels like it has the most potential, to me. Especially if you include an "indefinite" option. Right now, a lot of realms are chicken !@#$, and barely anyone dares to throw the first stone and start a war. If their previous peace agreements had been automatically terminated by the game, it could make the next steps much easier in some cases. For example, if two realms agreed to "end their war for the next 4 months", well there'd be a whole lot of pressure against them resuming their war at the end of that, but if the game automatically brought them back to war... that could be a whole other story.
Of course, the main problem is just player laziness in wanting the moral high ground and dogpiling whoever dares to break out of the mold, but that's harder to fix.
