Jamie-Lynn Sigler and Jerry Ferrara Split

Jamie-Lynn Sigler and her Entourage costar Jerry Ferrara have split, Usmagazine.com has learned.

Sigler, 28, showed up solo to a Dec. 15 Los Angeles screening of It's Complicated.

"She came with a few girlfriends, and they drank wine all night. They looked like they were having a good time," a partygoer told New York's Daily News.

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This past Thursday, she also hit Susan Sarandon's NYC ping-pong bar Spin with pal Lance Bass and went shopping in the Meatpacking District on Friday. Later, they checked out Broadway's Burn the Floor, which stars Bass' former Dancing With the Stars colleagues Maksim Chmerkovskiy and Kym Johnson.

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Meanwhile, Ferrara, 30, spent this past Saturday night at West Hollywood club Voyeur, where he and costar Kevin Connolly mingled with the ladies.

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"Kevin and Jerry arrived around 11 with a group of girls," a clubgoer tells the Daily News. "They were dancing and hanging out and didn't leave until after 2 a.m."

Sigler and Ferrara have been romantically linked since October 2008, but Sigler (who was previously wed to A.J. DiScala) always kept mum on their relationship.

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"[Jerry Ferrara] is a very special person, and I'll leave it there," she told Page Six magazine last year. "I'm not a good dater. It takes a lot for me to even want to kiss someone. I have to have a connection, and those are rare for me."