Poem found here: "Perhaps not to be is to be without your being" by Pablo Neruda
The poem is untitled. Or rather, the first line of the poem is the title of the poem, and even with the first lines there seems to be an identity crisis, "Perhaps not to be is to be without your being." Not in the sense of the serious existential who am I crisis, but this one is born out of identity of a couple and self -- which is just a serious, but not as deep.
The speaker defines what it means to be without in the next couple of lines, "without your going, that cuts noon light / like a blue flower, without your passing / later through fog and stones," note how the images are very image and nature based bringing a pastoral sense, and note as well that, by using nature, there's a greater expanse of loneliness exhibited, "without the torch you lift your hand / that others may not see as golden,"
Now by going of the sense of sight, this line, "that perhaps no one believed blossomed / the glowing origin of the rose," brings the other up to the divine -- the source of the good in nature -- kind of like a Persephone figure, but I'm not thinking this is a "poetic allusion" poem. The straight comparison is what the speaker feels -- she lights up his life and others as well.
"without, in the end, your being, your coming, / suddenly, inspiringly, to know my life, / blaze of the rose-tree, wheat of the breeze" The key here is "to know my life" and how expansive her knowledge and her sight is to the speaker -- "and it follows that i am, because you are:" the simple declaration like Descartes "I think therefore I am"
Then Descartes concept this applies to love with, "it follows 'you are', that I am, and we: and, because of love, you will, I will / We will, come to be." Note how the speaker doesn't state the other doesn't exist without him. Rather there's a bigger plain of existence as a couple.