Both had been single for a while and were looking for something fun, they told hosts Kyle and Jackie 'O' Henderson.
Her relationship with Nick Jonas was also a hot topic in 2011 and 2012.
This has led to companies removing their advertisements, findings of serious breaches of the Industry Codes of Practice and Guidelines, and to his firing from Australian Idol.
Despite the complications, Kyle told listeners the proposal went ahead without live music, explaining to then-girlfriend Tegan, 35, that they were attending a pop-up art show.
They are now the proud parents of two gorgeous kids together, sons Hudson, 3, and Archer, 1.
Live on air, you could hear the crowd cheer as the planes flew past.