If they don't agree and neither do the Ravens then nothing happens. If the Ravens agree but my partner doesn't then my partner stays silent and all I've agreed to do is shoot a confirmed Crow tonight, which hardly costs us the game. If the Ravens agree and my partner says they agree but then defects, that becomes game-throwing because I've already guaranteed that I will work to make the Ravens win in that scenario - which means that the cost of betrayal is too high to possibly justify it, allowing the Ravens to trust my partner regardless of personal character assessments.
In short, my plan is not game-throwing because nobody will have both ability and incentive to produce a state of affairs wherein it would become such.