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"Jennifer and Ben were apart for a few days earlier this week. They met up in N.Y.C. yesterday," the insider says. "Ben wanted to be by her side and attended the event. He watched her perform."
"They are always supportive of each other's careers," the source adds. "Ben has to be in Texas to film this coming week."
Affleck had been in Austin for production on his latest project, but made a stop in Los Angeles to visit his kids before reaching his final destination in New York.
On Saturday night, Lopez dazzled at the event, which took place across seven cities and six continents as a fundraising event for Global Citizen and Global Citizen's Recovery Plan for the World, a campaign to end COVID-19.
getty (2) Ben Affleck (L); Jennifer Lopez
Performing live from New York City's Central Park, Lopez opened with an energetic performance of "Cambia el Paso." She was then joined onstage by LL Cool J for "All I Have," followed by Ja Rule for their hits "I'm Real" and "Ain't It Funny."
Lopez's spectacular set also included fan-favorite "Jenny from the Block" and the unreleased song "On My Way" from her upcoming movie Marry Me, in theaters on Feb. 11.
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"It's always such an honor to be here with so many people, so many loving people, trying to do so many amazing things together," she said as the crowd chanted her name. "And because of that, tonight I want to do something special."
"Do you guys mind if I do a song that no one has heard?" Lopez asked the audience. "Because it's a special occasion, and I thought, 'What special thing can I do?' This song is about pushing through old mistakes and finding your destiny ... But this is just for you guys here tonight. I want to share this with you because I feel, I feel, what I know is that we are on our way."
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Earlier this month, a source told PEOPLE the couple is looking forward to seeing each other more, noting that while the two "have months of work coming up," they "plan on spending the holidays together."
"They will both get a break. For Jennifer, Christmas is all about the kids," the source told PEOPLE. "She makes it very special for them. She loves Christmas."
The insider added, "This year, it will take some more planning since Ben wants to be with his kids too. They haven't made any specific holiday decisions yet and are still working it all out."
Lopez and Affleck first got engaged in 2002 before they postponed their 2003 wedding days before they were set to walk down the aisle. The duo then officially split by January 2004.
They rekindled their love earlier this year and have been inseparable since, making their official red carpet return at the Venice Film Festival earlier this month.