03/18/2010 05:12 am ET Updated May 25, 2011

Britney Shares A Birthday With K-Fed's Girlfriend

While Spears hung with her sons at home, ex-husband Kevin Federline celebrated his girlfriend Victoria Prince's birthday -- which happens to fall on the same day as Spears's.

Federline, 31, and Prince, 27, had a late lunch at Mexican restaurant Casa Vega in Sherman Oaks, Calif. "She looked very pretty when she arrived for her bash," says an observer.

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