A source told People magazine that things "have been hard for months" for the Gomez, 25, and The Weeknd, real name Abel Tesfaye, 27.
"She and Abel have been going back and forth for a few months about their relationship... It's been hard with him being on tour and her shooting in New York. That wasn't easy on them."
The couple first started dating in January, before making their first official debut outing as a couple at the Met Gala in May.