Looks like Kate Hudson and Lance Armstrong have put the brakes on their hot, heavy and handsy romance. Us says the instantly serious squeezes have flamed out after more than two months of near-constant togetherness.

"There was no drama or ugliness -- they just decided to end things," an insider tells the mag. "There is no hatred, just sadness."

The alleged split comes just days after the actress joined the seven-time Tour de France champ -- and his parents -- at a high-profile summit for his Livestrong Foundation in Columbus, Ohio, where he implied that he might be interested in a political career.

According to Us, the PDA-happy pair realized at the conference that their fling had been flung.

Not that there haven't been signs of trouble brewing in the relationship, which kicked off in May, just after Hudson split -- yet again -- with Owen Wilson.

A big-eared Chicago Sun-Times spy overheard Armstrong respond to a query about Hudson at a July 21 cancer awareness event by pointing out, "I'm single," which, the snitch says, he then repeated, "kind of like he was trying to make a point."

Kate and Lance step out in New York on June 15.

Meanwhile, the New York Post claims the couple's "constant bickering and their travel schedules drove them apart," alleging that they recently had a "big blowout" that resulted in a communication breakdown.

"They didn't talk for, like, five days," says a mole.

Still, Kate, 29, and Lance, 36, covered a lot of ground during their brief but intense interlude.

They made their public debut in mid-May by spending quality time in Lance's hometown of Austin with his three children.

Then it was off to the south of France for Memorial Day weekend, where they made out and gazed into each other's eyes at a swanky bash.

A couple of weeks later, they turned up in Ontario, Canada, where Kate cheered Lance on during a charity ride and the two got in some alone-time at a vacation home belonging to the actress's mom, Goldie Hawn (the previous summer, she was photographed there with her blink-and-you'll-miss-him boyfriend, Dax Shepard).

Then it was back to New York, where they enjoyed a blended family Father's Day brunch with Armstrong's kids and Hudson's ex-husband, Chris Robinson, the father of her 4-year-old tyke, Ryder. 

In late June, Kate and Lance headed west, where they were spied puckering up on a Los Angeles tennis court, lunching with Goldie and snuggling over dinner in Santa Barbara.

Still, there was speculation right from the start that the duo's joined-at-the-well-toned-hip status would have the life span of a pair of Armstrong's spandex bike shorts.

"Lance is great in the beginning with women, but then they quickly discover how self-centered he is," a cycling source sniped to the Chicago Sun-Times in May (Armstrong's exes include designer Tory Burch and Sheryl Crow; he has denied reports that he tried to suck out Ashley Olsen's tonsils). "He has this thing for finding famous women -- successful in their own right -- but then he wants them to put their careers in second place to taking care of him and his needs."

Hudson, meanwhile, has made it clear that she's looking to settle down.

"I can't wait to have more [kids]," she told Britain's Sunday Times in April. "I'm at that place when I'm ready to have another one and Chris and I are not together. I'm like, 'Oh no! Uh-oh! I'm ready.'"

Added Kate, "Any guy I ever meet is always going to come second to my son. And you get to weed out the boys from the men. You definitely know which ones are the boys."