Final answer:
Based on the symptoms described, potential medical diseases that Forrest's life-long love, Jenny, may have passed away from in the 1980s include cancer and neurological disorders like Alzheimer's disease.
Step-by-step explanation:
Based on the information given, it is difficult to determine the exact medical disease that Forrest's life-long love, Jenny, may have passed away from in the 1980s. However, the symptoms described such as a gradual wasting away of the person and partially cataleptical affections could potentially indicate a few possibilities. Two potential medical diseases that could be considered based on these symptoms are cancer and neurological disorders such as Alzheimer's disease. It's important to note that a proper diagnosis cannot be made without further information or a medical examination.