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-inspiring moment as the crowd realized what was happening.

“You are the most incredible, brilliant, caring, creative, utterly chaotic person I’ve ever known,” Blue said. “You make every single day an adventure that I want to last forever.”

Then, stage right: A person emerges wearing a mildly terrifying bear costume. Looks like something off the Donnie Darko discount rack. The man is later identified as Bobb Hawkey from South Philly, an extra in Rigoletto and friend of the couple who had been charged with holding the ring. (Costume was an inside joke about a “ring bear.”)

Blue, down on one knee before his beloved.

“Will you marry me?” he asked Robillard.

She said yes. No hesitation.

After the curtain fell, the cast erupted in cheers.

You might call it an “operaposal,” says Frank Luzi, Opera Philadelphia’s VP of marketing.

Or not. That term probably won’t catch on.

Blue, 27, said he had told Robillard, also 27, that Rigoletto — Opera Philadelphia’s first full-production run at the Academy of Music since the beginning of the coronavirus pandemic — would be the perfect time for their parents to finally meet.

He didn’t mention the whole getting-engaged thing.

“As I realized they were coming, I thought, ‘Why not invite everyone?’” Blue said. “I told Ashley this is a great opportunity just to see the people we haven’t seen during the pandemic — while secretly letting every single person except her know the real reason for them to be here.”

Ashley Marie Robillard last appeared with Opera Philadelphia in 2019 as Musetta in La bohème. The Inquirer’s David Patrick Stearns gave her glowing reviews at the time: “As the flirtatious Musetta, Ashley Marie Robillard, from the Curtis Institute, sang with beauty and precision even in her most comic moments. Hers is the voice I’d most like to hear again.”

In Rigoletto, Blue played the Duke of Mantua, a philandering scoundrel who has a thing for his jester’s daughter. It doesn’t end well.

But Robillard said the Academy of Music, a stunning opera hall built in the mid-19th century, was a fitting place to say “yes” to her future husband.

“Philadelphia has been my opera family,” Robillard said.

Backstage, she was ecstatic, wearing her grandmother’s ring as an engagement ring. She had to sit down to take a breather before the couple rushed off to a massive dinner with dozens of family and friends.

While it was no secret they planned to get married, Robillard said she didn’t know Blue was going to pop the question on Sunday.

“I’m so sorry if any of the swearing got picked up by the mic,” Robillard said with a laugh.