The heiress and the music producer have been dating since November 2011 but friends have claimed Afrojack - whose real name is Nick van de Wall - has been so busy traveling for work that their relationship has suffered.
A source told RadarOnline.com: "Afrojack is extremely busy with his gigs and plays nightly at clubs all over the country, and Paris isn't going to go on the road with him and be a groupie."
Meanwhile, Paris is said to be jealous of former close pal Kim Kardashian's relationship with rapper Kanye West, both because it is going so well and because Kanye is a bigger star than Afrojack.
The insider added: "Adding to Paris' angst is that attention that Kim is getting from dating Kanye. Paris has been dating DJ Afrojack, but he's nowhere near the fame league that Kanye is in, and adding to that, the relationship has now cooled. He didn't accompany Paris to Cannes and he didn't go with her to Las Vegas for Memorial Day while he was working in Atlantic City."
Recently Afrojack - who is working with Paris on her new album - called her "one of the most talented performers I know".
He said: "The thing is with her ... she's like one of the most talented performers I know. She may not be a Celine Dion, but she knows how to perform on stage. She knows how to sing, believe it or not.
"In the studio with her for the first time, I wasn't sure what to expect, but the girl can sing. And she loves dance music so we made some nice music. And it was fun. That's the most important thing to have fun with the people you like."