现在海枯石烂曾经海誓山盟
[xiàn zài hăi kū shí làn céng jīng hăi shì shān méng]
This implies enduring love or loyalty ('till the seas dry up and the stones crumble'), contrasting with past passionate vows made between lovers. It's an expression that combines the imagery of constancy over time with memories of strong past promises.