Stefan / BACKGRID
What are BFFs for?
In May, Gomez, 26, had joined Swift, 29, onstage at her concert at the Rose Bowl in Pasadena, California. The two sang Gomez's hit "Hands to Myself."
The singers have been good friends for more than a decade. In 2015, Gomez joined other members of Swift's "squad" of celebrity friends in her "Bad Blood" music video.
In July, Swift was unable to be with Gomez on her 26h birthday, but did celebrate from a distance with a birthday cake in her honor.
"Will I let distance stop me from celebrating my best friend's birthday?" Swift said on Instagram. "I mean, I could but why would I want 2?"
See more cute photos of Gomez with Swift over the years.