Sonnet XLIII by Edna St Vincent Millay

What lips my lips have kissed, and where, and why, 
I have forgotten, and what arms have lain 
Under my head till morning; but the rain 
Is full of ghosts tonight, that tap and sigh 
Upon the glass and listen for reply, 
And in my heart there stirs a quiet pain 
For unremembered lads that not again 
Will turn to me at midnight with a cry.
Thus in winter stands the lonely tree, 
Nor knows what birds have vanished one by one, 
Yet knows its boughs more silent than before: 
I cannot say what loves have come and gone, 
I only know that summer sang in me 
A little while, that in me sings no more. 

This sonnet is in the petrarchan form, which follows an abbaabba cdecde rhyme scheme -which this poem fits almost perfectly, but for the minor hiccup at the end, where it follows a cdedce rhyme scheme, simply flipping the endings of tree/me and one/gone. Although it deviates from the typical rhyme scheme a bit, the volta comes in the same place. In between lines 8 and 9, starting with "Thus in winter..." is where the sonnet begins a shift. Petrarchan sonnets generally have the first octave have a question or an observation, while the sestet answers or comments upon the observation. In this sonnet she uses the sestet to comment on her observation made in the octave, where she observes that she does not remember any of her past lovers or that she does not remember how they made her feel, is commented upon after the volta, where she muses that though she cannot remember each and every one of them, she still feels a sense of loss, that they are not there and that she cannot feel the love that she once felt for them. This muted sense of loss was what made me pick this poem - not because I particularly share her feelings here, but mostly that I like the idea that was expressed. It is simply her musing on an abstract sense of loss, not specifically because she misses any single one of her lovers but rather that she misses how they made her feel. At least platonically, I can sympathize with her. It was an interesting idea, at least.