Despite claims that it was a casual affair or flirtation, Page Six has learned that Robert F. Kennedy Jr. and New York Magazine scribe Olivia Nuzzi had “incredible” FaceTime sex.

Sources tell us that Nuzzi was at first disgusted by the Kennedy scion after he made a clumsy pass at her back in October.

But — after they began talking over text — he “love bombed” her, and she quickly fell so madly in love with him that she lived a double life for nearly a year, sharing long calls, endless texts and virtual sex with the former presidential candidate, all while engaged to her partner of almost a decade.

In fact, multiple insiders say Nuzzi — even after Kennedy denied their affair in the press and even after he implied that he might sue her — is still in love with him.

Sources say that when Nuzzi was assigned to interview Kennedy — who was then running for the White House but has since dropped out of the race to endorsed Donald Trump — he insisted they do it on a hike in the Los Angeles area.

We’re told that Kennedy — who is married to the actress Cheryl Hines — “grabbed her arm” during the walk, apparently as a romantic overture, and that Nuzzi pointedly said that she and her fiancé, Politico journalist Ryan Lizza, often hiked together.

The magazine’s Washington, DC, correspondent later told a wide group of friends, including an editor at New York, that she was freaked out by his sudden gesture because they’d been alone in a secluded area when he made the move.

An insider tells us that Kennedy later sent her what she felt was a somewhat eerie message, saying that he had “wanted to tell her something” on the walk, but didn’t know if he was able to because he didn’t know if he was free to speak off-the-record.

He also sent her a photograph of himself. (It doesn’t seem as if it was a sexual picture).

Before the story came out, the journalism wunderkind had to speak to Kennedy several more times to do additional reporting and fact-checking — which, we’re told, is when the tenor of their relationship dramatically changed.

A source says that Nuzzi said to Kennedy — the son of assassinated attorney general Robert F. Kennedy, and nephew of President John F. Kennedy — in a text that next time she was in LA, perhaps they could go hiking again, but this time with their respective partners.

We’re told that Kennedy quipped that Hines only likes to go hiking “in the mall.” (A source close to Nuzzi denied that she suggested they go hiking with their partners).

Insiders say that as they exchanged texts over the following days and weeks, she became “infatuated” with Kennedy, and that friends even noticed her personality seeming to change over the months they were in contact.

“He love-bombed her,” said a source, “He’s done it to lots of women — claimed he can’t live without them. He told Olivia they’d be together after the election.”

(Another source said that, while he may have been implying that they could have an in-person relationship after the election, he always made it “quite clear” that he would not leave Hines for her).

A different source says that the Daily Beast alum told friends about a man she seemed bewitched by, without mentioning his name. Still others say she was surprisingly open about the romance, while Kennedy boasted about it to pals. We’re told three “gossipy” media friends knew the details.

We’re told that at times Kennedy would suddenly cut off communication between the two, which seemed to make Nuzzi even more anxious for contact with him. “He seemed to want to be in control,” said a source, “He’d set the rules for their interactions, and then of course he’d break them.”

A source says that during the periods they were in contact, “Olivia told multiple people that they told each other they loved each other [over the phone] every time they talked.”

They had “incredible” sex over FaceTime, according to another source, with Nuzzi noting to pals that the 70-year-old had impressive sexual stamina.

We’re told that Lizza became aware of the romance by August and confronted Kennedy by phone.

Sources say that Nuzzi’s pals are stunned that she seemed ready to risk her career, and turn her life upside down, for the sake of the exclusively phone-based relationship.

Nuzzi was put on leave by New York editors after they confronted her about the relationship. The mag said in a statement that it reviewed Nuzzi’s work, and found “no inaccuracies nor evidence of bias,” but it ordered a third-party investigation into the matter.

Lizza has recused himself from coverage of Kennedy. He declined to comment for this story.

Kennedy’s campaign has said that he “only met Olivia Nuzzi once in his life for an interview she requested, which yielded a hit piece.”

Hines hasn’t commented, but has appeared in public without her wedding ring since news of Nuzzi’s suspension broke.