"Elin was impressed with him from the beginning and eventually fell in love with him," a source tells PEOPLE
Chris Cline and ex Elin Nordegren started off as neighbors before their relationship developed into a romance.
The billionaire coal magnate, who died alongside his daughter Kameron in a helicopter crash on Thursday, first met Nordegren — who was previously married to Tiger Woods, with whom she shares two children — in 2011, when she bought a property next to his in Florida, PEOPLE previously reported.
“Elin was introduced to Chris by a local friend because they seem to have a lot in common,” a source told PEOPLE in 2013. “They both have children, like to keep their personal lives quiet, believe in philanthropy, and enjoy leisure outdoor activity.”
Cline, who would have turned 61 on Friday, and Nordegren, 39, would go on to travel together to Haiti on a church mission in 2012 and she also did work with Place of Hope after he introduced her to the child-welfare organization.
What started off as a casual friendship between the pair went on to blossom into a romance.
“Elin was impressed with him from the beginning and eventually fell in love with him,” a source tells PEOPLE.
“He was crazy about her, too, but he had children, responsibilities and demanded privacy that he didn’t always get when Elin was around,” the source adds.
Prior to their split in 2017, the pair were seen together on multiple occasions at Grand Cay, a private island estate in the Bahamas — which is where Cline’s helicopter departed from before the deadly July 4 crash.
“I saw them several times together on the island over the years,” Roosevelt Curry, who owns local lodge Rosie’s Place, tells PEOPLE.
“They looked very happy together, definitely a couple,” he adds.
In an interview with PEOPLE in 2014, Nordegren demurred on her relationship with Chris.
“Chris and I, since we’ve been close, have decided not to talk about [it],” she shared, adding, “I’m happy.”
Although Cline often visited Rosie’s during his trips to the island, the owner tells PEOPLE he did not see the billionaire this time around.
“I really liked Chris, he was a fine person who loved the Bahamas,” Curry says. “His death was an accident, and is a great loss to me and to Grand Cay. He was a helpful and generous person, he was nice and supported many functions over here.”
In addition to having recently built a house on the island, Curry tells PEOPLE that Cline had also refurbished the house there where President Richard Nixon used to vacation.
“Chris liked to sportfish and enjoy his time here, he will be sorely missed. Everyone here liked him,” Curry adds.
While en route to Florida, the small helicopter carrying Cline, his daughter, and five other passengers smashed into the ocean off the coast of the Bahamas.
“I still can’t believe it,” Greg Cline, Chris’ older brother, told The Palm Beach Post on Friday. “It’s like a dream … We were so close, all of us were.”
In a separate statement released to PEOPLE, the Cline family confirmed the passing of Chris and Kameron, and spoke about the absence their deaths will leave.
“We are all so deeply saddened … This loss will be felt by all those who had the privilege of having known them,” the family said. “We love and miss them dearly but take comfort knowing they are with God now.”
Chris, who would have turned 61 on July 5, was worth $1.8 billion, according to Forbes, having sold a $1.4 billion stake in his company Foresight Energy in 2015.
His daughter Cameron, 22, had recently graduated from Louisiana State University, her uncle Greg told the Post.
The crash is currently under investigation.