PHILADELPHIA — Rigoletto is an opera in three acts that, according to Opera Philadelphia, is about “fate, revenge and the abuse of power.” An audience of 1,200 at the Academy of Music on Sunday afternoon were treated to a surprise fourth act that involved duplicity, conspiracy — and romance. Just after the singers took their final bows, tenor Joshua Blue, who is making his debut with the opera company, called his girlfriend, Ashley Marie Robillard, to the stage. “Ashley Robillard, to stage. Paging Ashley Robillard,” he said into the microphone. He had a question to ask. It was an awwwww-inspir…
