"There is absolutely no wedding talk or planning going on," a source close to the couple told RadarOnline. "Publicly the couple is saying it's because they are just too busy with work, but if they wanted to get married, it would happen."
"The relationship is definitely at an impasse," added the source. "Either it's going to fizzle out, which seems likely, or they get married."
Jennifer and Justin at the Oscars in 2013
Fans of the couple, who have been engaged for 18 months, have also noted that they have not been seen together since December.
Jennifer, 45, and Justin, 42, were photographed enjoying a romantic break in Mexico but have not been spotted out in each other's company since.
It was also noted in earlier this month that the pair were apart over Jennifer's 45th birthday.
On 11 February the Along Came Polly star spent her special day with best friend Courtney Cox, while Justin remained in New York.
The Friends co-stars were spotted dining with Tobey Maguire's wife Jennifer Meyer and Jennifer's hairstylist Chris McMillan at the trendy Soho House in Los Angeles.
Jennifer also chose to stay in LA while Justin attended Philip Seymour Hoffman's Manhattan funeral on 7 February.
Justin is currently working on new HBO show The Leftovers in the Big Apple and was seen filming on set during the day of Jennifer's birthday. Later that night the director and screenwriter attended the Deth Killers of Bushwick store launch party in downtown Manhattan with Orlando Bloom, who separated from his wife Miranda Kerr late last year.
Fans will be eager to see if Jennifer and Justin attend the Oscars together on 2 March as they did in 2013.