In an opera filled with gorgeous music, it’s hard to beat the end of LA BOHEME’s Act One, with the trifecta of arias about young love. If only tragedy and sadness weren’t going to catch up with the central pair, Mimi and Rodolfo, and their friends, in the succeeding three “tales from the Bohemian life” (as the work’s source material was called). But wait. Director Yuval Sharon to the rescue, with a version that just finished a successful run at Opera Philadelphia, playing out the story in reverse.