It is the one moment every man wants to get right -- and which London floor-fitter Lefkos Hajji could hardly have got more wrong.
The luckless 28 year-old's dreams of giving his sweetheart, Leanne, 26, the ultimate proposal have literally vanished into thin air.
Hajji, of Hackney, east London, had concealed a 6,000-pound engagement ring inside a helium balloon. The idea was that she would pop the balloon as he popped the question.
But as he left the shop, a gust of wind pulled the balloon from his hand and he watched the ring -- and quite possibly the affections of his girlfriend -- sailing away over the rooftops.
"I couldn't believe it," he told The Sun newspaper.
"I just watched as it went further and further into the air.
"I felt like such a plonker. It cost a fortune and I knew my girlfriend would kill me."
Hajji spent two hours in his car trying to chase and find the balloon, without success.
"I thought I would give Leanne a pin so I could literally pop the question," he said.
"But I had to tell her the story -- she went absolutely mad. Now she is refusing to speak to me until I get her a new ring."
He is hoping the ring will still turn up.
"It would be amazing if someone found it," he added.
(Reporting by Peter Apps. Editing by Steve Addison)