心落深海久溺不回情入他心久伴不离
[xīn luò shēn hăi jiŭ nì bù huí qíng rù tā xīn jiŭ bàn bù lí]
'Heart Fallen Into Deep Sea Drowned Without Return Love Enters His Heart Accompanied Forever'. It describes a feeling akin to sinking into someone else's heart/ocean - a metaphor of being deeply in love. The speaker feels like they cannot get out, but also wishes to stay forever with the person loved.