Styles, 17, confirmed his separation from the Xtra Factor host last Friday (January 27), saying of the split: "[It] was a mutual decision. She is one of the kindest, sweetest people I know."
The couple are believed to have parted ways so that Styles could launch a career in the US with One Direction, but sources have predicted that they will soon be drawn back together.
"Harry's relationship wouldn't have gone down at all well in the States," an insider told Now. "There was a fear that it could damage their reputation before they'd even got started.
"It's sad, but Caroline knew it wouldn't last forever. They'll still be friends and haven't ruled out getting back together - she keeps saying he'd be the perfect man in ten years' time."
Styles and Flack were first romantically linked in October. Their 15-year age gap attracted a strong amount of criticism from celebrities and Flack even received death threats from One Direction fans.