Tweet causes ‘Nemi' to start trending
The pair have been friends for some time and, despite rumours that they’ve been secretly dating, they’ve always denied a romance.
Yet Niall‘s message to the US X Factor judge couldn’t have been more affectionate.
@ddlovato happy birthday honey!‘ Tweeted Niall, 18.
Have a lovely day! See ya soon‘
Demi, 20, responded, @NiallOfficial thank you sweet stuff! 🙂‘
The loving exchange caused so much excitement on Twitter that the term Nemi‘ was soon trending.
But Niall, who spent the weekend partying at V Festival, is too exhausted to say more.
Soooo tired today!‘ the 1D lad told his Twitter followers.
SEE PICTURES Niall Horan and One Direction sign copies of album Up All Night in New York
SEE PICTURES Niall Horan with One Direction and red carpet guests at the Brits 2012
VIDEO: One Direction’s Harry Styles supports Cancer Research UK
VIDEO: One Direction coming soon
VIDEO: Teen Now meets One Direction part 1
VIDEO: Teen Now meets One Direction part 2
VIDEO: One Direction at Capital FM Jingle Bell Ball part 2