in my spanish campaign, on easy campaign/VH battle, just about every faction bordering me (with the exception of the italian states and france) declared war on me within 4 turns of eachother. the sad part is, half of these were my protectorates. none would accept peace, even with large sums of money and military access included.

i think that a protectorate should not DoW on you unless it has at least 5 times the amount of provinces it had when it became your protectorate.