Lost+as+a+candle+lit+at+noon

In the poem, I Am Not Yours, the phrase, Lost as a candle lit at noon is talking about how she knows she is not loved by this man. She is so in love with this man, that is the only thing that is on her mind. What this phrase means is that she is not lost because she knows that she is not loved by this man. She is as clear as a candle, which means that she is not lost. Yet she is lost in him with love.