Niall Horan and Zoe Whelan

One Direction's Niall Horan is officially single again.

The 19-year-old pop star has split with 18-year-old Dublin model Zoe Whelan, his on-off girlfriend since bringing her to his brother's wedding in March.

A source told the Mirror: “It is all over for Niall and Zoe – and it is completely because of his side of things.

“Obviously, it was always going to be hard to have an ongoing relationship when his job has him travelling around so much.

“But there’s been no push from Niall to keep things going at all and he has told Zoe it is over by completely blanking her.

“Over the past few weeks her modelling career has become huge, but Niall hasn’t been in contact to say well done. She hasn’t even had a text from him, let alone a call, for nearly two weeks.

“Out of respect to Niall, she refused to say a word to anyone about the relationship – even when there was money on the table to spill the beans as she knew it would be over then.

“But it seems just doing her job is too much for 1D’s people, who appear to have pressured Niall to cut all ties with Zoe. It’s cruel the way he’s done it, and she’s obviously a bit devastated it’s over.”

However, the Andrea Roche model may find it's all for the best. Zoe has revealed she receives constant death threats from One Direction fans.

She said: “I still get hate mail and death threats.

“I’m strong though and stuff like that just makes you stronger.

“To think that people spend so much time being so negative, writing nasty things and doing mock-up photographs and setting up haters of Zoe Whelan pages, it’s really sad.”