Justin and Hailey Bieber are going ... by his recent birthday celebration with his closest friends and family members, the musician and the businesswoman seem to be happy together.

"Happy Birthday @pattiemallette I love you so much!!" Related: Hailey Bieber Sweetly Shouts Out Her Husband Justin and Baby Son Jack: 'My Boys' In the comments section, many fans couldn’t help ...

A source tells PEOPLE that the couple are doing "great" Justin Bieber had a low-key birthday ... their room was adorned with ...

"happy birthday," she wrote, alongside a white-heart emoji. "love you tons." Justin Bieber Says He's Going to Teach Son Jack Blues to Skate as 'Soon as Possible': 'It's Never Too Early' A few of ...

Justin, for his part, wore all-black and sang into a microphone as the duo sat in front of a trio of "Happy Birthday" balloons. Hailey captioned her upload, "31 ." Hailey Bieber Is Trying to Be as ...

Another said, "HAPPY LIFE JUSTIN!!!!!" A third added, "Jack is so cute." Someone else commented, "Happy 31st birthday Daddy ...

Justin's wife Hailey Bieber also shared her husband's post on her Instagram Stories and wrote. "Happy Birthday @pattiemallette I love you so much!!" Hailey Bieber Sweetly Shouts Out Her Husband ...

Jerritt Clark/Getty Images Justin Bieber had a low-key birthday this year ... "Their marriage is fine. They're very happy together." On March 1, Justin shared a rare look at his life as a new ...