First there's denial when the cactus won't talk to anyone about its problems and grows bigger and bigger spines in an attempt to keep everyone at a distance. Then, rationalization: The cactus thinks "I'm as good as they are!" and blooms madly in an attempt to make its point. Next, there's bargaining when the cactus tries to take all the resources for itself, grabs every bit of water and nutrients within reach. And then it swells up and turns orange, like a big pumpkin. Finally, acceptance.... but its too late.
Its best not to put your cactus through this emotional turmoil in the first place. And always maintain a good relationship with open communication because it may save their lives.