it's a card, not a warning system. for now the whole coalition breakdown system just feels too random and too sudden, i know it might be messing with "balance" but realistically you should know when your coalition partner starts to resent your policies, especially if you have good relations with them.
alternatively a "tiered" resentment system can be implemented with cheaper cost at the first vote of no confidence threat (maybe a mere 1-2 resource or a minister spot) but one "repeat offense" would result in a progressively increasing cost