With both the Everwar and the Against the Tide galactic achievements, when they are completed, all wars are automatically ended.  Why?  As a player, I should have the option to seek peace with any civilizations with whom I want to seek peace and continue to engage in war with those with whom I want to continue fighting.  The reason is, I cannot just declare war again immediately, I have to wait for some number of weeks to pass (25?) before I can declare war again.

My suggestion is that, at the successful conclusion of these 2 galactic achievements, I should be congratulated and informed that I can now seek peace if I so choose.  The wars should not automatically be ended.