Taylor Swift "freaked Conor Kennedy out" by coming on too strong.
The singer, 22 - who has dated a host of Hollywood hunks in the past including Taylor Lautner and Jake Gyllenhaal - and the schoolboy started dating during the summer but Conor, 18, is said to have called things off because Taylor got too serious, too fast.
"Conor's just an 18-year-old kid and wasn't ready for anything super serious," a source told RadarOnline.
"But Taylor is looking for her soulmate and it kind of freaked him out with how strong she came on."
It comes as it was reported the pair have split up.
The couple are said to have amicably broken up "a while ago", but that there are "no hard feelings" between them.
"They quietly parted ways a while ago. It was just a distance thing. No hard feelings. They're fine," a friend told Us Weekly.
It is thought Taylor and Conor had not seen each other for more than a month as the singer has been busy promoting her fourth studio album Red, which was released on Monday.
Soon after she started dating Conor - the son of Robert Kennedy Jr and the late Mary Kennedy - Taylor bought a $US4.9 million, 13-room property in Hyannis Port, Massachusetts, across the street from his grandmother Ethel Kennedy.
A realtor confirmed the purchase of the house - which was originally "way overpriced" and listed for $US14 million - saying: "It's in a beautiful location and right across the street from Conor and the Kennedys.
"It's a beautiful home. She got a nice home, paid fair price. The house was on the market for two to four years."
Taylor's purchase came just days after she introduced Conor to her parents in Nashville, Tennessee.
While they were there, the pair also enjoyed a date at a diner and onlookers said they couldn't keep their hands off each other.
However, Taylor rarely speaks openly about her private life, preferring to write down her feelings in her song lyrics, and has never confirmed the pair were dating.