深情似海真心一片溺我心海此生不换
[shēn qíng sì hăi zhēn xīn yī piàn nì wŏ xīn hăi cĭ shēng bù huàn]
Meaning 'With a love as deep as the sea, and unwavering sincerity, I'll remain devoted forever without changing.' This expresses an intense, eternal loyalty and affection toward someone.