What are the speaker's underlying feelings in "Tonight I Can Write"? How do you perceive the speaker?

This poem by Pablo Neruda explores the melancholy the speaker feels over his lost love: "Tonight I can write the saddest lines." The night has inspired the speaker to reminisce about his lover and their very passionate relationship: "I kissed her again and again under the endless sky. "However, on a deeper note, the speaker appears to be more in love with love! "I no longer love her, that's certain, but how I loved her." As such, the speaker truly is sad over the  passing of love and contemplates the  impermanence of passion between a couple as the woman will "...be another's. As she was before my kisses."

Neruda explores the transient nature of passionate love with nostalgia yet also, paradoxically, clearly explores the reality of those lovers who do not seek permanent relationships: "...this be the last pain she makes me suffer and these the last verses I write for her." The speaker needs the pain of lost love to pen his verse and evoke deep emotion. Your perception of the speaker will depend upon how you feel about a man who needs his lost lover to use as his muse to write poetry!

What is the speaker's final attitude in "Tonight I Can Write"?

As with many people who've gone through a painful breakup, the speaker of Neruda's poem is finding the situation difficult to handle. So much so, in fact, that his attitude towards his former lover changes rapidly throughout the poem.

At a couple of points in the poem, the speaker openly states that he no longer loves her. Yet it soon becomes patently obvious that, despite what he says, he still holds a torch for the woman who has clearly had such a profound impact on his life.

In his vivid physical description of his former lover—her “bright body,” her “infinite eyes”—the speaker reveals, even if he doesn't intend to, that this was a very special woman indeed, someone who meant an awful lot to him.

Eventually, as the speaker comes to the end of the poem, he makes it clear that his former lover is still making him suffer a great deal of emotional pain. This would not be possible if he didn't love her or, at the very least, if he didn't have any residual affection for her.

That being the case, we must take the poem's final lines at face value:

Though this be the last pain that she makes me suffer
and these the last verses I write for her.

It is not unreasonable to expect that the speaker will go on to write, whatever he might say, more verses for his former lover. It is hard to believe, to say the least, that someone he loves so deeply, someone who's had such a profound effect on his soul, will no longer inspire him to greater poetic heights.