No wonder he's Jealous! Nick Jonas's girlfriend Olivia Culpo shows off the sexy body that won her the Miss Universe title as she joins the star poolside in Miami

She is a former Miss Rhode Island, Miss USA and Miss Universe.

And on Friday, Olivia Culpo showed off her beautiful, award-winning body in a string bikini as she joined her rock star beau Nick Jonas by the pool at his Miami hotel.

The 22-year-old slipped on a long black and white knitted cardigan over the top, left unbuttoned to reveal her slender figure in all its glory.

She carried a large cream leather Prada handbag that matched her Oxford shoes as she found a spot by the pool.

Nick, also 22, wasn't dressed for a swim or sunbathe, clad in a black T-shirt and black jeans, his ripped abs - which he recently displayed on the cover of Flaunt magazine - sadly kept under wraps. 

He met his gorgeous girlfriend at the Miss USA competition in 2013 and they have been dating for just over a year.

The former member of boy band The Jonas Brothers is forging a solo career and he was taking time to relax before his performance at the Fontainebleau Hotel later that night.

It is one of the stops on his Nick Jonas Tour, in support of his new self-titled album, which is due out on November 11.

He has already released a track from it, called Jealous, about finding it hard to see other men checking out his girlfriend. 

Olivia stars in the music video for the single, and looks stunning as she plays her cello in a high-waisted bikini.

In one scene he plays a taxi driver who picks up Olivia and a man and enviously watches them together in his rear view mirror.

Eventually, Nick – who released the video on his birthday on September 16 – gets the girl, and she sings the track while sitting next to him.

Nick recently said of the song on the Today show: 'I think what's great about this song… is that it opens up the conversation that men are afraid to have. Jealousy happens and it's OK.'

The star's other high-profile girlfriends have included Miley Cyrus, Selena Gomez and Delta Goodrem. 

It's almost a year since The Jonas Brothers - Nick, Kevin, 26, and Joe, 25 - split on October 29, 2013, breaking the hearts of their millions of fans. 

Nick started his solo tour on October 5 at The Crofoot in Pontiac, Michigan. He has gigs planned in Los Angeles at The Satellite on October 29 and the Troubadour the following night, before flying to New York to play the Gramercy Theatre on November 4 and the Music Hall Of Williamsburg on November 5. 

On December 5 he will be back in LA at the Staples Center and on December 11 he will perform at the Blue Cross Arena in Rochester, New York. (Sources from http://www.dailymail.co.uk/