(Cover) - EN Showbiz - One Direction's Niall Horan is reportedly experiencing "a classic case of sloppy seconds."

The singer was said to be dating Demi Lovato, but it seems that Niall has had his sights set on another for quite some time.

Niall is rumoured to have been seeing model Alahna Aldridge, his bandmate Harry Styles' ex, for several months.

"It's a classic case of sloppy seconds - Harry dated Alahna first," a source told Radar Online.

"Until January this year, Harry and Alahna were seeing one another but there was nothing serious going on.

"Then, just a few months later, Alahna became smitten with Niall and they have been dating ever since."

Harry doesn't have any hard feelings about Niall and Alahna's romance.

"Harry was a little put out at first he was sweet on Alahna and he's not used to losing out on a girl to another guy," the source explained.

"But, despite the initial tension, all was forgiven and Harry told Niall he was happy for him. It's not as if Harry is short of female attention himself." (C) Cover Media