情不知所诉九念而不忘情不知所起一往而情深
[qíng bù zhī suŏ sù jiŭ niàn ér bù wàng qíng bù zhī suŏ qĭ yī wăng ér qíng shēn]
'Not knowing where to express this feeling nor from where does deep attachment originate, but never forgetting it even after countless thoughts.' It's about inexplicable yet profound and long-lasting feelings of longing.