The pair met on The X Factor two years ago where Danielle was a backing dancer.
A friend of Liam, 19, said: “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.
"He has hardly been able to see Danielle in recent months and the band have a world tour next year so it was only going to get harder.
"They ended things but Liam hopes they have left on good terms. She was the first real love of his life."
Danielle, 24, has been getting abuse from obsessive One Direction fans for months and last week one fan sent her a death threat.
Liam responded by blocking the fan and angrily saying he would “take it further” if anything more was said.
In April after more threats, Danielle wrote on Twitter: “To tweet someone telling them to ‘go die’ is disgusting.
"I don’t care if you hate me but keep it to yourself rather than tweeting me."
However, sources close to the band say Twitter trolls attacking Danielle were NOT the reason she split from Liam.
It was more to do with the fact he simply doesn’t have time for a girlfriend.
The split will send shock waves through the whole band as Danielle is close friends with Louis Tomlinson’s girlfriend Eleanor Cole and the pair often message each other on Twitter.
Do you believe this breakup RUMOR?