BRITNEY SPEARS dumped fiancé Jason Trawick because he wouldn’t even have sex with her, say sources.

“Britney has always wanted a little girl and she hoped that Jason would be the man to make her life complete,” said an insider. “But in the past few months, their relationship has been spiraling downward.”

The troubled love affair had lasted over three years, but finally, on Jan. 11, Britney, 31, broke down in tears and announced in a press release that she was splitting with Jason for good.

The pair started dating in  2009, and he popped the question on his 40th birthday in December 2011. But things went downhill after that.

The ENQUIRER reported in late October that Britney’s friends predicted she would call off the wedding because she felt Jason was faking the romance. But she was still in love with him, and over the holidays started telling pals they’d wed in the spring.

“Britney kept pushing Jason to set a date for the wedding,” revealed the insider. “But he just didn’t want to talk about it, telling her he was too busy working to set a date.

“She was so desperate to marry him she was even ready to elope. But the more Britney pushed for marriage, the more Jason pulled back.

“And their love life went straight down the tubes, although Britney did her best to seduce him. She’d try to provoke Jason to have sex at the worst times, while he was on a business call, in her ‘X Factor’ dressing room, and even in the car while being driven by a bodyguard.

“Despite Jason’s rejections, Britney never gave up. She thought she loved him and held out hope he was the man who could finally make her happy and give her more children.

“Finally, in a showdown, Jason yelled at her, ‘I don’t want to get married and I don’t want children!’ By that time it almost didn’t matter because they were already sleeping in separate bedrooms.”

Along with her dad, Jason was co-conservator of the emotionally fragile singer, who is mom to sons Sean, 7, and Jayden, 6. And now sources say he’d grown tired of baby-sitting her.

He’d also grown weary of helping her handle her role as an “X Factor” judge, a job she ultimately gave up to get back into the studio, according to the sources.

“Jason became her keeper, and being her lover fell by the wayside,” said the insider.

“But she was the star and wasn’t going to let him leave her. If anything, she was going to leave him. So through her publicist she got in first and announced their relationship was over.”