沧海桑田成全了最终海誓山盟变作了曾经
[cāng hăi sāng tián chéng quán le zuì zhōng hăi shì shān méng biàn zuò le céng jīng]
Great changes in time made the final oaths sworn on the sea change into past events. This indicates that once serious promises have become part of history due to significant changes over a long period, highlighting the fleeting nature of time and commitments.