By LILY JOBSON, SHOWBUSINESS REPORTER Published: 18:41 EDT, 3 August 2026 | Updated: 18:48 EDT, 3 August 2026 Olivia Dean is said to have turned down the chance to headline Glastonbury next year as she plans to focus on writing new music instead. The Rein Me In singer, 27, was reportedly offered the opportunity to play at this year's festival, where her former love interest Harry Styles is tipped to perform. Harry is heavily rumoured and is bookies' favourite to headline the Pyramid Stage at the upcoming festival. Olivia is instead hoping to play at the 2028 gig but her decision to not perform has 'nothing to do with Harry'. After his…