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Sources tell E! News that 25-year-old Lavigne and the Hills star have been seeing each other quietly over the last couple weeks.
"They're hooking up," an insider said, "but they're keeping it low-key."
Not so low-key that they haven't been seen in public, however. The pair, who both became single late last year, were first spotted at dinner at Koi on Feb. 4. According to a restaurant source, the "Sk8ter Boi" warbler and 26-year-old hunk left together in the same car and drove to club Voyeur.
They were last seen out again on Thursday, back at Voyeur, where they partied all night.