Wire Image / WENN 1 / 7
Wire Image / WENN 1 / 7

At least Scarlett Johansson didn't wear white. But she did commit a wedding faux pas at Reese Witherspoon's weekend nuptials to CAA agent Jim Toth by stealing a bit of the spotlight from the bride and groom.

Seems the Ryan Reynolds-divorcing starlet, 26, invited rumored squeeze Sean Penn, 50, to be her plus-one at Reese's romantic knot-tying Saturday at her ranch in Ojai, Calif., a move that has raised the stakes on their burgeoning relationship.

"Scarlett is Jim's client but no one, including the bride, knew she would have turned up with Sean Penn," a ScarJo pal informs PopEater. "Turning up at a wedding with your boyfriend is definitely a huge statement, especially that wedding. What it's doing is announcing to the whole of Hollywood that they are serious."

To their credit, the footsy-playing, nicotine-addicted amours waited until after the ceremony to give in to their touchy-feely instincts.

Us Weekly reports they hit a nearby bar to nosh and have a nightcap, ordering pizza and sandwiches washed down with gin and tonics.

The liquor probably came in handy, considering that everyone in the bar was rubbernecking, according to a spy.

And even though she makes her living as a performer, ScarJo, sheathed in a black dress topped with a shawl, felt flustered by the gawkers.

"This is so terrifying," she supposedly whispered to Penn as he took her hand and led her to a table.

Her nerves must have calmed down pretty quickly, however, because Us says that by the time the table was cleared, Scarlett was comfortable enough to situate herself in Sean's lap.

Soon after, they commenced the make-out portion of the evening, sucking face "in full view" of the other patrons for a good 15 minutes.

"Scarlett is head over heels in love with Sean," a snitch enthuses to PopEater. "She normally tries to hide away from public attention, but when she's with Sean, she doesn't care."

The age-challenged pair were first spotted together in January, and since then, they've enjoyed everything from a cozy south-of-the-border getaway to a romantic dinner with friends.

On the surface, the fresh-faced starlet's attraction to the crankypants, paparazzi-hating Oscar winner seems like a head-scratcher.

But insiders say they actually have common ground, including a mutual interest in Haiti (he's lived in the earthquake-devastated region on and off for more than a year) and a fondness for graying temples.

"She looks to Sean as an older, sexy, college-professor type," a source recently told Star. "She thinks he's a genius, and she's totally into him."

Back in February, Johansson's rep denied the dating rumors, insisting that she and Penn, whose on-again, off-again divorce from Robin Wright was finalized last year, were simply longtime friends.

RELATED: Details on Reese's nuptials

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