回忆再美好那只是曾经
[huí yì zài mĕi hăo nèi zhĭ shì céng jīng]
The translation would be 'Even if memories are beautiful, they're just of the past.' This expresses a reflective feeling of remembering fond past experiences while recognizing they belong only to a bygone era, evoking nostalgia or even a tinge of regret about lost moments.