Political coalitions have cyclical patterns of breaking-up that start with interest groups coming together to oppose common foes and they then end with the falling out of the coalescing parties.
This happens irrespective of whether the coalitions achieve their objectives. If they win, the partners quarrel over the spoils, hidden ideologies, and claims of being short-changed. The challenge for each coalition is for the dominant party to refrain from hoarding everything while keeping the others - those who feel cheated - within the fold.