The couple that sweats together, stays together!

Justin Bieber and Hailey Baldwin held hands as they made their way into boxing class in Hollywood yesterday, and JB even demonstrated a few of his jukes and moves on the way in. Guy knows a thing or two about hitting the bag!

These two seem blissfully happy together, which is maybe why Selena Gomez is still struggling to come to terms with the fact The Biebs is a married man.

"She’s still heartbroken. I don’t know if she’ll ever be over Justin," a source dished to In Touch magazine.

"She’s never felt so lonely in her life. It’s been rough. The exchange of gifts, kissing under the mistletoe, decorating the tree together, and other romantic gestures… it’s hard not to think of Justin. [Selena] finds it upsetting that this year she’ll be replaced by Hailey and is having difficulty trying not to imagine all the nice things the newlyweds will be doing together. She’s learned coping mechanisms in her previous rehab stints, but she forgets and she suffers a setback," the source added.

Selena and Hailey fought over the Canadian crooner for years, so the model must feel like she won a contest now that she's Mrs. Bieber!