海誓山盟变作了曾经沧海桑田成全了最终
[hăi shì shān méng biàn zuò le céng jīng cāng hăi sāng tián chéng quán le zuì zhōng]
'Oaths as eternal as the sea and mountains have become past experiences; changes over time fulfill everything.' Here, it means that grand promises from the past now seem like ancient history and that time has led to a certain fulfillment despite changes.