Taylor Swift apparently ended things with Harry Styles because he's a "massive flirt".
The country singer and the One Direction star enjoyed a brief romance, even celebrating Taylor's birthday and Christmas together.
However, the pair called it quits earlier this month and reportedly it's due to the 18-year-old's wandering eye.
"Taylor's trust issues contributed towards their argument. She says she couldn't cope with all the attention Harry gets from fans, and the fact he is a massive flirt with girls," a source told British magazine Star.
"She knew that if they were to spend huge amounts of time apart, trusting him to remain true to her would be pretty much impossible."
Having celebrated her 23rd birthday last month, Taylor is more than four years older than the curly-haired heartthrob, who turns 19 on February 1.
It seems the significant age gap could have contributed to their break-up.
"She thinks he's just too young to settle down and is having too much fun playing the field," the insider continued.
"Taylor was also sick of getting nasty tweets from his fans about how they shouldn't be together."
During their relationship, the pretty blonde was targeted on the social networking site by jealous One Direction followers, who even bombarded her with death threats.
Harry has since been seen frolicking with US TV star Hermione Way on Sir Richard Branson's Necker Island, while Taylor put on a brave face for her Golden Globes red carpet appearance.
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