Why do people cancel weddings at the last minute?

Golfer Rory McIlroy has called off his engagement to tennis star Caroline Wozniaki.

McIlroy said the sending of wedding invitations made him realise he "wasn't ready for all that marriage entails."

So why do people cancel weddings at the last minute?

David, who was jilted by his fiancé and Keith, who jilted his fiancé, shared their stories with BBC Radio 5 live's Breakfast.