He finally found actual peace. Peace that he thought no one could ever interrupt or take away from him. The Hulk finally received the one thing that he always wanted, he was content. Both of them did, even Banner was content with his life on Sakarr, he loved Caiera just as much as The Hulk did. He could have lived out the rest of his days in happiness, never hurting anyone.
Then it was torn away. It was torn away by the same people who gave it to him. That made The Hulk angry, it made him angrier than he's even been. Only this time he had Banner working with him, not against him.