Insiders say that Liam's hectic schedule is to blame, as he is on a world tour with One Direction until November.
A source told The Sun: “They have been trying for months to make it work but it just hasn’t. They had a big chat last month and decided there wasn’t any point in dragging it out.
“Liam’s on tour until November and Danielle’s very busy so they basically never see each other.
“It was extremely amicable though, which is good because there’s a strong chance Danielle will still be in the lads’ upcoming 3D film."
The couple first got together after meeting on 'The X Factor', where Danielle was a dancer when One Direction were competing on the show.
Their break up last September was blamed on similar reasons, with a source telling The Mirror: "They have split in the last few days because it has been more and more difficult to keep the relationship going with Liam spending more and more time away."