The couple found keeping up a long-distance relationship difficult

Nicole Scherzinger and Lewis Hamilton have ended their five-year on-off relationship.

The couple are said to have split because racing driver Lewis, 28, is based in Switzerland, while The X Factor judge Nicole, 35, is often in her native US.

‘It’s so hard to keep up a relationship when they’re barely in the same country as each other,’ says a source.

‘Both have supported each other in their careers and will continue to do so. But the nature of their work ultimately cost their relationship.’

The unhappy news comes a day after Lewis missed out on a prize at the British Grand Prix because he suffered a puncture which caused one of of his tyres to rip.

It was only a few weeks ago that the Hertfordshire-born sportsman had said he was close to proposing to Nicole.

‘We’ve been together for five years, which is quite a milestone,’ Lewis told The Sun.

‘But hopefully in the near future. Maybe before we get to six years.’

A spokesperson for Nicole has confirmed the split.

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SEE PICTURES Nicole Scherzinger at the 2011 Fox Upfront Presentation

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Anna Duff