It's the battle over the prenuptial agreement that's causing a ruckus.
Justin and Jessica began dating in 2007, following Timberlake's bust-up from actress Cameron Diaz. After splitting last March, the notoriously private couple reunited late last year.
J.T. is widely reported to have proposed to J.B. during a holiday vacation to Wyoming in December. But chatter over how to divide their assets has reportedly caused the pre-wedded bliss to hit a sour note.
Star magazine snoopsters say Justin and Jess have been butting heads over everything from division of property to becoming parents. Justin's alleged dalliances with fanboy fave Olivia Munn and actress Olivia Wilde are also creating drah-mah.
"She thinks if he strays during the marriage, she should be royally compensated. She wants a fidelity clause in the prenup giving her at least $500,000 if he does," a squeal reveals.
Justin has reportedly agreed to a one-time cash settlement, but he's refused to budge on the issue of adding a fidelity clause. The "SexyBack" star has also reportedly balked at the idea of ponying up monthly spousal support.
"If he's faithful for several years, maybe she'll agree to have his baby. She doesn't trust him 100 percent yet. Jessica figures if she gets fat during the pregnancy, he'll cheat again."
There were certainly no signs of trouble as the future newlyweds partied during a Saturday Night Live afterparty at New York City's Ristorante Asellina over the weekend. The couple looked affectionate all night, according to onlookers.
Revelers oohed and aahed as the brunette bombshell sported her engagement ring for the first time publicly. J.T. was spied wearing what appeared to be an engagement band.
"[They] were very lovey all night and kissed a few times," a spying guest told People magazine.
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