Lavigne, who turned 30 on the 27th, rung in her new year at The Bank Nightclub in the Bellagio Resort and Casino in Las Vegas. The "Girlfriend" singer looked festive for the night of celebrations, wearing a bright pink strapless minidress with a gathered waist.
She wore her light blonde hair down and in waves, and rimmed her eyes with her trademark black eyeliner.
While she was surrounded by friends and loved ones, including her sister-in-law Amie Lavigne and a group of her closest gal pals, Kroeger, 39, was noticeably absent from the party.
"It's over," a source told Us. "He has been going around L.A. telling people that they are divorcing."
The rockers were married just over a year ago, exchanging vows in the South of France in July 2013. Kroeger first proposed to his singer love in August 2012 after they were dating for just a month.
Despite her marital problems, Lavigne was in good spirits on Saturday, an onlooker tells Us, adding that she was dancing up a storm with her girlfriends, happily posing for photos, and eating frosting off of her massive birthday cake.