Taylor Swift can do it with a broken heart — but with boyfriend Travis Kelce by her side, she doesn’t have to.

Fresh off their most public display of affection yet, the pop superstar and her Kansas City Chiefs star beau are stronger than ever as they head into the summer, a source close to the couple tells PEOPLE in this week’s cover story.

“They really are very, very happy together,” the insider says. “They’re very serious about each other, and the relationship feels different for both of them.”

Fans got to see their playful nature up close and personal on June 23, when Kelce carried Swift, 34, onstage during an introduction to her song “I Can Do It With a Broken Heart,” off her record-breaking latest album The Tortured Poets Department.

During the segment, Kelce, 34, powdered Swift’s face and showed off a few dance moves while dressed in a top hat and tuxedo alongside her dancers.

“They have so much fun together, and it just works,” the source says of the couple. “It’s funny to their friends because at first everyone wondered what they had in common, but you realize how similar they are. They both wear their hearts on their sleeves and are all-in with everything they do, whether it’s with career, family or friends.”

For Swift, her focus remains on her Eras Tour, which recently spent three nights at Aviva Stadium in Dublin, Ireland. (Fresh off the plane from L.A., Kelce entered the stadium mid-way through the final show and was seen mingling with Julia Roberts in the VIP tent.)

Swift is next scheduled to play a trio of shows in Amsterdam starting July 4, and will stay on the road until December, when she wraps her record-shattering tour after more than 150 shows.

“That feels so far away from now, but then again, it feels like we just played our first show on this tour because you have made this so fun for us,” she told the crowd in Liverpool on June 13. “It’s taken over everything. I think I once had hobbies, but I don’t know what they were anymore because all I do when I’m not on stage is sit at home and try to think of clever acoustic song mashups.”

Kelce, meanwhile, will report to training camp for the Chiefs on July 21. The team will play their first game of the 2024 NFL season on Sept. 5 versus the Baltimore Ravens.

“Football is definitely still his priority but so is his relationship,” the source says. “He makes romantic gestures to show he’s thinking of her when they’re apart. She’s going to try to attend as many games as possible.”

Meanwhile, a second insider says Kelce was “thrilled” to be able to join his Grammy-winning girlfriend in London.

“They loved being onstage together,” the source says. “He is confident and fun, and it was one of her tour highlights.”

The “Karma” singer and the tight end were first linked in September, when Swift made a public appearance at a Kansas City Chiefs game. They’ve since taken their love international, with trips to Australia, Singapore, Italy and more.

In an episode of the Bussin’ With the Boys podcast that was recorded on June 19, Kelce opened up about their relationship like never before, revealing how Swift seamlessly fit into his life amid his at-times chaotic football career.

“She understands situations like that, and I think that’s why I really started to really fall for her, was how genuine she is around friends, family,” he said. “It can get crazy for somebody with that much attention, and she just keeps it so chill and so cool. . . . She wants to be a part of it. She wants to support me.”