Pregunta:
Nostalgia is the suffering of thinking about something that was had or lived, about a stage that has changed. The second definition in the RAE (Royal Spanish Academy) defines it as "melancholic sadness caused by the memory of a lost happiness." But nostalgia is not always suffering and pain, is it?
Answer:
Yes, it is. However, sometimes it can be accompanied by love: nostalgia for past (or lost) loves and experiences. But in nostalgia, what is "lost" weighs more than the love. "Remembrance" is not the same as "nostalgia." Remembering past times as wonderful moments lived with love is not nostalgia. It becomes nostalgia when the feeling of "that is lost" outweighs the "experience of love lived."
Nostalgia: Entre el recuerdo doloroso y la melancolía positiva