is it normal that diplomacy never works and whenever you share a border with a faction that faction is 100% likely to attack you instantly with stack after stack?

its taking me forever to finish my arverni campaign because i cant move east until i conquer all of western europe, i conquered aedui, romans and sweboz (they dont accept ceasefire/protectorate even when they have 1 province left and are offered a huge sum of money) now carthage are attacking me too, after i wipe them out i will have to do so with the lustonians and britons too i guess.

although the only territories i need to win the campaign is france and central europe, i have to conquer all of europe to win, where is the fun in such a long winded campaign