It is sometimes funny how one can be brutally reminded of the cruel beauty of some poetry, through paths most improbable. If you don't know this poem, I recommend its reading. It's quite deceivingly simple.
(ObPedantic: most sites list it as "Villanelle" but my f&f has it as "But I Can't". It is however a perfect villanelle, except for the penultimate line which is slightly off on purpose).