Sonnet, Free Verse
It is nearly impossible to retain the meter of the original language when translating poetry. On occasion translators attempt to do so, but the gap is nearly unbridgeable. Because of that, we won't talk about the meter of the translation and we'll jump right into the original.
Neruda’s poem is a sonnet, a distinguished and popular poetic form with fourteen lines. There are many different types of sonnets, but the two most common are the Petrarchan and Shakespearean or English sonnet. You might be familiar with the man who gave his name to the Shakespearean sonnet, but there's also a man behind the Petrarchan form. Francesco Petrarca (1304-1374) wrote many sonnets about a mysterious woman named Laura, and he's often credited with popularizing the sonnet form.
The Petrarchan sonnet is divided into two parts. The first eight lines are called the octave and usually pose a problem of some kind. The last six are called the sextet, and they generally offer some kind of resolution to the problem posed in the octave. Problem-focused coping, here we come. This shift in gears between the octave and the sextet is often called the volta, or turn. Can you find it in "Love Sonnet 17"?
Neruda's poem follows this form pretty well: it is divided into two quatrains (a group of four lines), and then two tercets (a group of three lines). This is basically an octave and a sextet, right? The first eight lines are filled with metaphors, as the speaker tries to explain his love (the problem). The last six lines show us that the speaker is resigned to the fact that it's just not possible (resolution). This certainly isn't your normal problem-resolution, but hey, nothing about Neruda's sonnets is normal.
… But Without the Rhyme
In a normal Petrarchan sonnet, the octave's rhyme scheme is usually ABBA ABBA, and the sextet can have a variety of rhymes schemes (two common ones are CDE CDE and CDC CDC). Well, Neruda didn't like these options. In fact, he didn't seem to like any option: his poem just doesn't rhyme. It does include a couple rhymes (think "tierra"  and "manera" ), but it's not sustained throughout the piece. Why do you think Neruda chose not to rhyme this poem?