爱我多深似海吗久居海底你不懂
[ài wŏ duō shēn sì hăi ma jiŭ jū hăi dĭ nĭ bù dŏng]
This phrase expresses profound unappreciated love. The user suggests loving someone so deeply (as deep as the sea) and staying in such love so long (deep-sea residence implies enduring time), while pointing out the beloved one doesn’t comprehend the depth of this devotion.