Travis Kelce decided to post pictures of him and Taylor Swift on Instagram because he wanted to show "how serious things have become"

A source told PEOPLE: "It wasn't random. It was intentional. They've been private in their own way, but this was his way of showing how serious things have become."

"They're in a really solid place and more in sync than ever."

Travis shared 13 images of himself posing with loved ones and seven of those pictures included Taylor.

He captioned the set: "Had some adventures this offseason, kept it 100."

Flavor Flav commented: "The whole world happy for y'all,,, may God continue to bless you and your families with happiness and pure joy," while Erin Andrews wrote: "FAVS".

And, a comment from the official Kansas City Chiefs account said: "things we love to see: travis happy."

Last year, Taylor, 35, shared pictures of Travis, 35, to her grid for the first time, when she posted a selfie that also featured the athlete, Prince William, Prince George and Princess Charlotte at her first London Eras Tour show at Wembley Stadium.

Meanwhile, Taylor took to her own Instagram account to share her support for her boyfriend's new movie Happy Gilmore 2.

Travis appears alongside Adam Sandler in the sequel and Taylor shared the film's poster and wrote: "Happy Gilmore 2 had me cackling and cheering the whole movie. An absolute must watch. 13/10, go watch it on @netflix as soon as humanly possible."

Travis also posted a picture of himself with Sandler and wrote: "Man this life is crazy!! Still so surreal I got this opportunity. @adamsandler SANDMAN!! Thank you brotha, for the opportunity and for giving us all Happy Gilmore 2! Everybody go check it out right now! On @netflix #happygilmore2."