When a TV series saw the ending, it was sad because it was a common phenomenon of human emotional experience, that is, feeling lost and reluctant to part with the end of the process. When watching TV dramas, people would usually put themselves in the character's shoes and imagine that they were experiencing this process. When the ending appears, the character's life and relationships will change. This kind of imagination can make people feel a strong sense of loss. In addition, television dramas often presented a beautiful beginning and a hopeful ending, which might also make people feel disappointed and sad. People's emotional experiences are complex and can be influenced by many factors, including personal experience, cultural background, expectations, and so on. Therefore, it wasn't the drama itself that made people feel sad, but rather the people's personal emotional reactions.