But the pair – who have decided to give their love another chance four months after splitting – soon found themselves caught up in danger.
Their stay on Richard Branson's £60-million private Necker Island took a dramatic turn when Hurricane Irene hit.
Lightning struck the Virgin tycoon's eight-bedroom Great House, which burst into flames.
Kate and her boyfriend – pictured last year – plus her two children Joe and Mia were among the 20 people staying in the property. All thankfully escaped unharmed.
The Hollywood actress turned real-life hero during the ordeal – scooping up Sir Richard's elderly mother into her arms and carrying her outside to safety.
Speaking about Kate's commendable actions, the Virgin Tycoon told ITN news: "It was she who carried my mother out of the house.
"She said it was like being on a film set where you’re waiting for the words 'cut' but they just don’t come. So it was quite surreal for her to be in a real-life situation.
She carried my mum out of the house. My mum is 90 and can walk but it was more just to speed the process up than anything else."
"But anyway, she was great. She swept her up into her arms and got them out of the house as fast as possible."
Sir Richard, who was staying in a villa about 100 yards away from the main house when disaster struck, posted pictures on his website to show the damage done to the house.
"The main house is completely destroyed and the fire is not yet completely out," said the 61-year-old.
"My office was based in the house and I have lost thousands of photographs and my notebooks, which is very sad. But all family and friends are well – which in the end is all that really matters."
The businessman's 29-year-old daughter Holly was also staying in the house.
She was due to get married on the island in November, but representatives have been unable to confirm if the nuptials will still go ahead there.
Kelly Brook was among the celebrities reaching out with messages of support.
She tweeted: "Sending you all lots of love. I am so sad to hear what happened. I have fond memories there xxxxxx"
Friends of the family say The Duke and Duchess of Cambridge have also been in touch to say how sorry they are.