The Mysterious Prince's Happy Medical Concubine

The former voiceless Yuan was famous all over the world for being stupid and fat. Suddenly one day, everyone discovered that Yuan Qingyin had changed. The fat all over her body was falling off at a speed visible to the naked eye. She seemed to be pretty good-looking. A marriage was granted to the prince of Guangping, who was about to die soon. Yuan Qingyin originally thought that being a widow was not bad, with no house fights, no parents-in-law, and no worries about food and drink. This little life should not be too comfortable, but how come her husband, who promised to die, was not dead, and was still very lively?