Just anecdotally from my own life, they become more like thinking back to a dream you had last night. There is a knowledge of, or a familiarity with the emotions, but a lack of definite certainty about the content. You know it's yours, you know what it meant, you know what you experienced, but without reality to guide you and only through memory. When you do experience the guidance of reality, through songs, words, sights, smells, then the clarity/intensity can also come back. And that doesn't fade or I wouldn't use that word, you can get so familiar to it that it isn't carrying the weight it once did. Loss feels like loss, shame like shame, love like love... It's not that it fades into nothing, or that the quality of it diminishes. It's more that you bought a summer coat but it's winter now, it's not needed anymore. Still beautiful, still wearable, still looking good on you, just that it isn't the right thing to wear right now.