When Matt Cawley popped the big question to girlfriend Stacey Scanlon, it’s fair to say it could’ve gone better.

“Just another chapter in the book,” said Cawley. “I was like ‘Here we go!'”

“I feel like it’s a story that’ll be passed along in our families forever,” added Scanlon.

They’re talking about the loss of a $9,000 diamond engagement ring — a family heirloom.

Cawley’s plan was to surprise Scanlon with the ring during a romantic walk along Lighthouse Jetty in South Yarmouth on Monday morning.

He tied it to a big sand dollar with some string, slipped it onto a rock when she wasn’t looking, and then slyly called her attention to it.

She grabbed the sand dollar, but the ring tumbled into the rocky nooks of the jetty — and vanished.

“You could just hear it go — click, click, click — down through the rocks,” said Cawley, a 30-year-old from Dedham who works in his family’s restaurant. “I knew it was gone.”

“It was just a freak accident,” lamented Scanlon, a 31-year-old schoolteacher from Needham. “I don’t understand why it happened to us. It’s one of those things ‘Why us?'”

The panicky couple summoned beachgoers, lifeguards — even Tom Flynn with his metal detector.

But four hours of searching proved fruitless.

“It was good even though we didn’t find it,” says the retiree. “Everybody helped. That couple will come back here on their anniversary and say ‘That’s where our ring is!’ It was quite the human interest story.”

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