Taylor Swift and Travis Kelce are "very serious about each other"

A source told PEOPLE: "They really are very, very happy together. They're very serious about each other, and the relationship feels different for both of them.

"They have so much fun together, and it just works. It's funny to their friends because at first everyone wondered what they had in common, but you see 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."

Travis is due to report to training camp for the Super Bowl winning Chiefs on July 21 but his relationship with Taylor is still a huge priority.

The source said: "Football is definitely still his priority but so is his relationship. 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."

And, Travis was "thrilled" to join Taylor in Europe for her 'Eras' tour and join her on stage in London.

A second insider said: "They loved being onstage together. He is confident and fun, and it was one of her tour highlights."

Speaking previously about their relationship, Travis talked about how supportive Taylor is.

He told the 'Bussin' With the Boys' podcast: "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. 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."