The insider tells PEOPLE that their relationship is “growing” in part because they support each other’s careers

Taylor Swift and Travis Kelce’s romance isn’t for show — his friends believe it’s the “real deal,” a source tells PEOPLE.

“Travis’ friends think this is the real deal for him,” the insider close to the Kansas City Chiefs star says exclusively. “They’re still a little shocked by all of it — that he’s dating the Taylor Swift, but they’ve seen how down to earth she is with his friends and family.”

The source adds that the relationship is “growing” because the NFL tight end, 34, and the music superstar, 33, both have found success in their own worlds — and they continue to appreciate one another’s accomplishments.

“They’re both really hard workers, and he acknowledges her art is hers, and he has what’s his,” the source tells PEOPLE. “He understands the territory their relationship comes with and like he said, isn’t letting any of the hoopla impact how they’re growing together.”

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The source adds, “Their relationship is about the two of them, and he sees Taylor for who she is and vice versa.”

For Kelce, that extended to seeing Swift in Argentina earlier this month, during the Chiefs’ bye week.

At the Eras Tour concert at Estadio Monumental (River Plate Stadium) in Buenos Aires on Nov. 11, Kelce could be seen enjoying Swift’s performance from a VIP tent, alongside her dad, Scott Kingsley Swift.

In fan-captured footage from the concert, the NFL star seemingly showed delight while he watched the singer perform “Karma,” in which she cheekily changed the lyrics to suit her suitor.

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“Karma is the guy on the Chiefs coming straight home to me,” Swift sang, causing Kelce to flash a huge grin.

After the concert, footage showed Swift rushing into the waiting arms of her beau as the two embraced and kissed.

Now, having wrapped the South American leg of her tour, the “Lavender Haze” singer has time off until February — all of which gives the couple time together as the holidays approach.

In a wide-ranging interview with WSJ. Magazine last week, the football player shared that life with Swift is a whole other kind of ballgame, and that he’s “never dated anyone with that kind of aura about them.”

“I’ve never dealt with it,” Kelce added. “But at the same time, I’m not running away from any of it…. The scrutiny she gets, how much she has a magnifying glass on her, every single day, paparazzi outside her house, outside every restaurant she goes to, after every flight she gets off, and she’s just living, enjoying life. When she acts like that I better not be the one acting all strange.”

He said that spending time getting to know Swift has been eye-opening, admitting, “I’ve never been a man of words. Being around her, seeing how smart Taylor is, has been f—ing mind-blowing. I’m learning every day.”