Reversible data hiding (RDH) for color images has attracted increasing attention in recent years. Due to its effective utilization of the correlation between prediction errors, high-dimensional prediction-error expansion (PEE) can achieve much better performance for color image RDH than low-dimensional PEE. However, existing studies only focus on high-dimensional PEE with nonadaptive embedding. To further improve the embedding performance for color images, we propose a novel three-dimensional PEE method that is adaptive to image content. Double deep Q-network (DDQN), introduced to RDH for the first time, is adopted to find the optimal mapping paths for PEE. In addition, an action selection scheme is presented for DDQN to efficiently find the reversible mapping paths. Extensive experiments show that the proposed method outperforms existing color image RDH methods in image quality.