"We've been together for five years," said Formula 1 driver Lewis. "which is quite a milestone really."
"…Hopefully in the near future," he added when quizzed about popping the question. "Maybe before we get to six years."
There have been previous hints that Lewis, 28, and Nicole, 34, will tie the knot. In 2011 Nicole spoke out against an engagement rumour that circulated.
"They came out with some rumor the other day," said Nicole in an interview. "Everyone was congratulating us, which was hilarious.
"We congratulated each other on our engagement when we weren't even engaged."
The couple celebrated their five year anniversary at the beginning of June, declaring their love for eachother in a series of cute Instagram photos.
With their hugely successful careers often keeping them apart, Nicole and Lewis made sure to spend some quality time together on their anniversary weekend, happily celebrated five years together.
The high-profile couple marked their anniversary on the beautiful island of Capri, with romantic Lewis posting a picture taken on their special day on his Instagram page.
The candid snap showed singer Nicole and Lewis looking excited as the prepared to board a helicopter together. With her arms up in the air, Nicole posed in a striped dress and a straw hat while her man stood by her side, a smile on his face.
Lewis's adorable pet bulldog Roscoe joined the couple, wearing his very own pair of ear protectors.
Nicole watches Lewis race in Monaco
In a caption to accompany the pic, Lewis wrote, " Me & my lady celebrate our 5 year anniversary in Capri, a time I will never forget. I love you babe."
The couple's sky-high adventure came after they enjoyed a cruise around the island together on a small motor boat. Happy and relaxed, they looked more in love than ever as they took in the beautiful surroundings.
A week before, on 26th May, supportive Nicole was in Monaco to cheer on Lewis as he took part in the Grand Prix there.