The NYPD had been looking for them since Saturday, after getting the ring out of the grate.
NY police issued a "WANTED" post for the mystery couple, posting on Twitter, "She said Yes - but he was so excited that he dropped the ring in a grate".
What the video actually shows: the woman, surprised and aghast, and the man, kneeling to peer down into the grate to see how far the ring had fallen.
Officers returned to the scene on Saturday morning, removed the grate and recovered the ring, then launched a social media campaign to find the couple. "Every argument between them will end with "at least I didn't drop the engagement ring down the sewer grate", a twitter user BigJim wrote". The couple left but the police managed to retrieve the ring.
"Thank you, Twitter. Case closed!"
When no useful response came from the two posts, they posted two pictures of the couple which would help people recognise them better. The tweet said the NYPD was making arrangements to return the ring.
But - after persistent searching - officers found the engagement ring, have cleaned it and are now attempting to track down the couple.
"Love, John, Daniella, and the NYPD". And when they ended up in Times Square, the ring fell off.
Another appeal was then put out, this time with images of the couple.
Police in NY found the engagement ring a couple from Peterborough lost after a proposal in Central Park.
"Wasn't a Twitter user, I am and will be forever grateful to all who have helped me get my ring back!"