Ashley Olsen, Lance Armstrong Shack Up at N.Y. Hotel

After riding to victory over cancer and to seven consecutive Tour de France titles, Lance Armstrong has now moved on to Ashley Olsen.

The new couple was spotted at New York hotspot Rose Bar on October 29 by an eyewitness who tells Us Weekly, "they were being very flirtatious."

The next night, the odd duo took in play Young Frankenstein. Lance Armstrong and Ashley Olsen then enjoyed dinner and wine at the Waverly Inn.

And while Lance Armstrong was preparing to run in last Sunday's New York City Marathon, the lovebirds shacked up at luxe hotel Soho House, where they both had booked rooms. Sounds like a full house... of love!

Sources tell Us Weekly, however, that 21-year-old Ashley Olsen shouldn't let herself get swept away by the whirlwind Big Apple romance.

"Lance is a candidate for a midlife crisis," says an unnamed source, who the magazine says is close to the divorced father of three.

Why, because he's in his mid-life? Or because he recently broke up with fashion designer Tory Burch and singer Sheryl Crow, to whom he was engaged?

"Next week, he'll be on to someone else," another insider says.

Maybe Mary-Kate Olsen? That would make for some interesting drama... not just between the twins, but between Lance Armstrong and Sean Avery.