A source claims the couple has decided to push back their planned December nuptials because of incessant arguments.
The insider added the romantic spark has faded and the singer and her former manager have drifted apart.
"Britney and Jason had planned to get married at the end of December, but they have been fighting non-stop so the wedding has now been called off. They are telling their friends it's being postponed, but they will probably never make it down the aisle,” a source told Radar Online. “Britney doesn't think Jason is any fun and resents him because he acts more like a second father than a romantic partner, or equal. They have been sleeping in separate bedrooms for a very long time. Jason feels like he is Britney's babysitter and it's pretty much just a business arrangement at this point. He does love Britney and the boys, but he just can't see himself spending the rest of his life with her."
Britney’s parents, Jamie and Lynne, are said to be "absolutely devastated” that the wedding has been called off.
The X Factor judge’s father is apparently especially disappointed because he feels Jason has been leading his daughter on.
"Lynne is very close to Jason and views him as one of her children. Meanwhile, Jamie feels that Jason shouldn't have proposed to Britney if his heart wasn't in it, and feels a little betrayed. It doesn't help matters that both Jamie and Jason are co-conservators of Britney. The whole situation is just sad for everyone," the source added.