THE RUNDOWNA source spoke to Entertainment Tonight about Justin Bieber’s relationship with his son, Jack, and how he supports his wife, Hailey Bieber, as they parent him.The comments mark a rare glimpse into Justin’s family life.Hailey spoke in multiple interviews last week about Jack, too.Hailey Bieber spoke in multiple interviews last week about her and Justin Bieber’s 16-month-old son, Jack Blues Bieber, and what he has taught her. While Justin primarily uses his music to express his feelings about parenthood, a source spoke to Entertainment Tonight today about how profoundly Jack has reshaped the singer’s life.“Jack is his whole world,” the insider said. “He’s happiest when he’s with Hailey and Jack, no matter what they’re doing. He’s been supportive of Hailey, and when she needs to travel for work, he really steps up with parenting. They’ve gotten into a good flow.”Earlier this month, Hailey revealed how Justin made her Rhode Australia launch trip possible. She had been discussing work-life balance during her Vogue Australia Forces of Fashion summit panel. “Having a great partner is really important, and sharing responsibilities,” she said. “I’m here working, and my son is at home with his dad, living his best life. Having that support is very freeing and makes the decision a little bit easier.”In her Vogue Australia interview, which was published on Friday, the entrepreneur shared that she is happiest with her boys. “Honestly, I feel the most fulfilled when I’m with my family, when I am with my husband, when I am with my son,” she said. “That is definitely the most whole I feel—when my family is complete and we’re together. But I also feel really passionate about getting to do what I love and getting to meet new people and work on Rhode and on this brand. That’s something that has felt really, really, really fulfilling for me and ignited this deep passion. Both of those things have been such a blessing in my life.”