They met on an airplane and fell in love across continents

He was a high school teacher from Boston. She was an Italian insurance worker. They met by chance, some 30,000 feet in the sky.

Flash back to summer 2015. Sean Kavanagh, then 29, was traveling to the Middle East to teach for the summer, stopping off in Portugal's Azores archipelago to see the bull-running festivities.

Kavanagh fell in love with these stunning Portuguese islands and their incredible culture and cuisine, not to mention the steep gorges, craggy cliffs and crystal-clear seas that characterize the landscapes.

Meanwhile, 27-year-old Anna Gorga was taking a break from the city grind to go horse-riding on this Portuguese archipelago.

"I was running from bulls and she's riding horses," Kavanagh tells CNN Travel. "We didn't run into each other, but we're on the same flight to Lisbon afterwards."

In fact, Gorga was supposed to be on an earlier, canceled plane.

Boarding her later flight, Gorga couldn't have known that this mundane moment of travel plans gone awry would spark an airplane-borne, continent-spanning romance.

Serendipitous meeting

"When I think back on how we met, it seems impossible," she says.

"It was pure coincidence, just a fortunate meeting," says Kavanagh.

Gorga was already seated by the window when Kavanagh boarded the plane. They didn't speak; they barely even noticed one another because of another passenger seated in between them.

"But after takeoff, the woman next to me asked if we'd switch, because she really wanted to look out the window," says Kavanagh.

He agreed and found himself sat next to Gorga.

He was struck by her infectious smile. She immediately noticed his charisma and charm.

"I just remember immediately, obviously, thinking he was very cute and very sweet," she says.

The two strangers started to chat. They surprised themselves by settling into an easy repartee. It started with their mutual love of the Azores and moved into more intimate territory: jobs, families, ambitions, desires.

When the flight landed in Lisbon, the conversation continued over airport coffee: It was apparent neither party wanted it to end.

But they had to say goodbye -- Bostonian Kavanagh was boarding a connecting flight to Israel to continue his travels. Italian-born Gorga was heading to Zurich, Switzerland, where she was living at the time.

They departed as friends -- but Gorga, who says she's an adamant realist, thought she'd never see this man again. They lived on different continents, after all.

"I thought: 'Yeah, he's really nice, but I'm much more down to earth, so this is not going to go anywhere.'"

Plus, there were other complications.

She wasn't looking to fall in love, she says. She was actually dating someone else at the time.

Still, the travelers left the possibility of continuing the connection hanging in the air.

"I almost jokingly said: 'Yeah, if you pass by Zurich, just let me know, we can have a coffee,' recalls Gorga. "And then he actually took it quite seriously."

Before the summer was out, Kavanagh had landed in Zurich and knocked on Gorga's door.

Long-distance lovers

After a whirlwind weekend in Switzerland, it was clear the couple weren't just acquaintances who'd met on an airplane. There was something tangible between them. They had to see one another again.

They arranged a long weekend together, wandering through orange groves in Valencia, Spain.

But as their summer drew to a close, they questioned whether it was just a summer romance? What about when fall came, and Kavanagh was back in the US?

They grappled with wanting to carry on seeing one another, and knowing how difficult it would be.

"You never know how willing someone is and how flexible they are to move around," says Gorga.

Still, the fact they'd met on an airplane indicated they both were enthusiastic about traveling -- and had the means to make it happen.

At first, their loved ones weren't convinced the connection would last.

"Of course, all your friends and family are rooting for you," says Kavanagh. "But I think they were kind of doubtful."

Gorga kept the budding relationship on the down low, not telling her family until she was certain it was going somewhere. She confided in friends, though, who couldn't believe Gorga had met a potential boyfriend on an airplane.

"They were joking that usually they sit next to really boring or annoying people," she laughs.