AH :
liddi is probably more familiar with the details and precise translations, but the title of the novel in Mandarin is more like "Eternally Yearning for You" and "Lost You Forever" is the title of the first volume of the novel.
The title of the novel 长相思 literally means Eternally Yearning for Each Other.
The word 相思 means the yearning / lovesickness is experienced by both parties, so it is not unrequited love.
Revised editions of the novel from 2019 onwards added a new subtitle for Vol 1. The pictures are from the most recent 2023 publication:
Vol 1 如初见 As When We First Met (red)
Vol 2 诉衷情 Love Confessed (green)
Vol 3 思无涯 Unending Yearning (blue)
The prose that goes with each title is as follows:
Vol 1 (the first part of the song Xiao Yao sang to lure Fei Fei)
君若水上风,妾似风中莲。If you are the wind above the water, I am like the lotus in the wind
相见相思,相见相思。Seeing and missing each other, Seeing and missing each other
君若天上云,妾似云中月。If you are the cloud in the sky, I am like the moon in the clouds
相恋相惜,相恋相惜。Loving and cherishing each other, Loving and cherishing each other
君若山中树,妾似树上藤。If you are the tree on the mountain, I am like the vine on the tree
相伴相依,相伴相依。Accompanying and relying on each other, Accompanying and relying on each other
君若天上鸟,妾似水中鱼。If you are the bird in the sky, I am like the fish in the water
相忘相忆,相忘相忆。Forgetting and remembering each other, Forgetting and remembering each other
Vol 2 (the 2nd part of the song Xiao Yao sang to lure Fei Fei)
缘何世间有悲欢 Why is there joy and sorrow in the world?
缘何人生有聚散 Why there are gatherings and separations in life?
唯愿与君 I only wish, with you
长相守、不分离 To stay together forever, never to part
长相守、不分离... To stay together forever, never to part...
Vol 3 (the song that is intrinsically linked to Chi Chen and A Heng's tragic love story)
请将我的眼剜去 Please cut out my eyes
让我血溅你衣 So my blood splashes on your robes
似枝头桃花 Like peach blossoms on the branches
只要能令你眼中有我 As long as I am in your eyes
请将我的心掏去 Please take out my heart
让我血漫荒野 Let my blood spill in the wilderness
似山上桃花 Like peach blossoms on the mountains
只要能令你心中有我 As long as you have me in your heart
It is commonly posited that the original title for Vol 1 (which is the title of the book) refers to Cang Xuan, Vol 2 to Jing, and Vol 3 to Xiang Liu. In some ways it makes sense, because in the early parts of the book particularly during the Qingshui town arc, both Cang Xuan and Xiao Liu constantly miss each other, reliving their happiest moments together in their childhood.