This is Ms. Eldering's runner up story in the Echelon Press's 2007 Fast and Fanciful contest.
Two sisters fight over a butterfly necklace, breaking it in half and leading them to separate lives. Each lives a life they have fantasized of living but as they change they keep feeling as if something is missing. Only in putting the necklace back together can they go back to the life they knew.
Feel the power of the butterfly.