To say it started with a kiss
is quite misleading and remiss,
and so these words I must retract,
it's quite the opposite in fact.
Take the answer now in mind
and think of that beguiling line
If it were true then, for the win,
strike the key used to begin.
This puzzle actually contains two answers and is self-referencing. You need an answer from the first verse to use in the second. The correct answer needs to explain the riddle and why it is correct. Happy puzzling!
The obvious answer is a single letter
but the title tells you that you need to get meta.
To be accepted your answer must be
a detailed explanation, logically.