Are Avril Lavigne and Chad Kroeger back together, or what?

The former couple, who separated in 2015 but never formally divorced, has apparently been getting quite cozy lately. The duo looked to be very affectionate at Clive Davis' Pre-GRAMMY Gala last month, and now they seem to be working together in the studio.

WATCH: Exes Avril Lavigne and Chad Kroeger Walk Red Carpet Arm-in-Arm at Pre-GRAMMY Party 

Lavigne was all smiles in this captionless photo, shared on Tuesday night, cuddled up next to her estranged husband on a white couch, each holding an instrument.

The 31-year-old also shared videos from the session, along with musicians Zane Carney and Stephan Hovsepian, showing off her newfound skill of mandolin-playing.

"Mandolin Happy @zaynecarney @stephanhovsepian and Chad," she captioned one of the clips.

PIC: Avril Lavigne Hits the Studio Again With Ex Chad Kroeger 

Lavigne and Kroeger first began dating in 2012 while working together on her fifth album. After just one month together, Kroeger put a ring on it and the pair wed in the South of France on July 1, 2013.

On September 2, 2015, Lavigne announced on Instagram that she and Kroeger had separated.

"It is with heavy heart that Chad and I announce our separation today," she wrote on Instagram. "Through not only the marriage, but the music as well, we've created many unforgettable moments. We are still, and forever will be, the best of friends, and will always care deeply for each other. To all our family, friends and fans, thank you sincerely for the support."

But this isn't the first time these exes have hit the studio together since their split. Lavigne shared a pic of Kroeger strumming a guitar back in October 2015 with the caption, "Back where it all started..."

PICS: Avril Lavigne Had the Ultimate Girls Weekend -- Complete With a Britney Spears Cameo 

While neither party has put their wedding rings back on, they did strike quite the couple-y pose on the red carpet last month.

And Lavigne even said she was "feeling great" and having a "lovely night" in an Instagram pic of the pair.

So, what do you think -- friendly exes making music, or a re-kindling romance? Sound off in the comments below.