Quite a few nations I liberated as Germany tried leaving the alliance. Serbia and Greece in particular. Well I re-invaded them and re-puppeted them, and the same event fires making them independent of me. I understand it happening the first time, but it doesn't make much sense to puppet countries if the game takes half of them away from me. Nationalist Spain was a particular sore point, as I spent a lot of manpower clearing a huge Allied presence from Republican Spain.