By Carlos Greer/New York City Kevin O'Donnell/New York City K. C. Baker/New York City reporting by Mike Fleeman/Los Angeles and Marisa Laudadio/Los Angeles
Updated September 10, 2012 12:00 PM

As far as summer romances go, this one will go down in history. It’s involved jet-setting (Cape Cod! Nashville! Boston!), ice cream, real estate and, of course, Kennedys. And not only has it changed the couple at the center of it all-Taylor Swift and Conor Kennedy-but it’s changed an entire town. Says a longtime Kennedy watcher: “Taylor’s brought a new zest to Hyannis Port.”

That’s nothing compared to the effect Kennedy has had on Swift herself. “She is head over heels into him,” says a source in Swift’s circle of friends. Despite the differences in their ages and where they are in their lives-she’s 22 and a megastar; he’s 18 and still in high school-the source says that the Grammy winner “is on cloud nine and is soooooo into him. She thinks she is in love.”

And it’s all happened rather, well, swiftly. It was just less than two months ago that the country-pop princess-who hobnobbed with Ethel Kennedy and her youngest daughter, Rory, at the Sundance Film Festival in January-was first spotted bonding with Conor (Robert F. Kennedy’s grandson) and the rest of the Kennedy clan over the July 4th holiday. Since late July the pair have spent nearly every weekend by each other’s side, either in Hyannis Port or Nashville. Their outings have progressed from grabbing pizza (their first public date on July 25) to a sailboat ride on Nantucket Sound, to a family wedding-and even a trip to the grave site of Kennedy’s recently deceased mother, Mary, where Swift comforted her boyfriend with hand-holding and hugs. There’s recent buzz that she’s purchasing a home in Hyannis Port, across the street from his grandmother Ethel Kennedy, leading to wild speculation the pair might elope. (Fun fact: Ethel was 22 when she wed RFK, who was 24.) “She thinks he could be the one,” says a source.

It’s enough material to fill a double-album’s worth of Swift’s trademark autobiographical love songs. “Some of her friends think it’s moving a tad bit fast,” says the source in her circle. “One of those rolling-of-the-eyes when they talk about it-as in ‘That won’t last; he’s too young for her.’ But they let her do her thing.”

Of course, not everyone’s so accommodating. In the midst of this love fest, Conor’s aunt Victoria Gifford Kennedy publicly accused the couple of crashing the Aug. 19 nuptials of her daughter Kyle at the Fairmont Copley Plaza hotel in Boston. Although Conor was invited, the mother of the bride claims he didn’t RSVP until an hour before the ceremony, when he texted and asked if he could bring his girlfriend. “I responded with a very clear ‘Please do not come,'” she told the Boston Herald. When the couple showed up anyway, she asked them to leave-twice. As etiquette experts debated the couple’s behavior during Wedding-gate, Victoria’s stepmother, Today cohost Kathie Lee Gifford-who attended the wedding-went on her show and confirmed the story. A Swift pal maintains the incident “must have been a big misunderstanding because anybody who knows Taylor knows she’s a superpolite person.” (Swift’s rep told the Herald the singer was invited and that the “bride thanked her profusely for being there.”)

If Swift and her boyfriend were embarrassed by the incident, they didn’t let it ruin their evening. After leaving the hotel, they hopped in a silver Mercedes and headed to Pomodoro, an Italian eatery in Boston’s North End, where they sat in a back corner, attempting to keep a low profile. While Swift-who wore a floral-print dress, pearls and her signature red lipstick-“looked stunning” says fellow diner Eric Stoller, Kennedy “looked like he was going to the prom, wearing his dad’s suit and tie, like a scruffy high school kid.” Indeed, it wasn’t the most romantic dinner. “He seemed nervous,” says Stoller, “and she seemed like she was more into her phone.”

Though she may not have found a fan in Victoria, Swift has nothing to worry about when it comes to the rest of the Kennedys. “The family has embraced her,” says a longtime Kennedy friend. “If you pass muster with Ethel, you’re in. She is the matriarch. If you don’t, you’re out.” For the record, Ethel, who rarely speaks to the press, has deemed Swift “amazing,” and the family friend says the relationship isn’t raising eyebrows among the famously tight clan. “Nothing is too fast or too surprising for the Kennedy family,” says the friend. “Ethel’s very live-and-let-live. If her grandson is happy, she’s happy and she’ll support him. That’s just how they are.”

Still, they don’t embrace just anybody. “They’re always very suspicious of being used,” says Laurence Leamer, author of The Kennedy Women. But as he notes, “I don’t think Taylor needs this to advance her career.” As for Conor’s motivation for dating the star, he asks, “What red-blooded 18-year-old wouldn’t want to be dating Taylor Swift? It’s not more complicated than that. Who [in the family] is going to wring their hands and say, ‘What’s going to come of this?'”

But as the summer winds down, that’s exactly the question on everyone’s minds. Will Swift, who is releasing an album in October, still have time for her boyfriend in the fall? Says the source in her circle: “She is focused on her music-but on him a lot as well.”