Hailey has denied there was any overlap in the relationships.
Justin and Hailey were first linked romantically in 2016, during a break in his relationship with Selena, who he'd been with on and off since 2010.
Justin and Selena called it quits for good in May 2018. Just two months later, it was revealed that the singer had proposed to Hailey, and the pair were married by September 2018.
Needless to say, the new photo of Hailey and Selena quickly went viral, with stunned fans sharing their reactions on Twitter.
The surprise display of unity comes just weeks after Hailey addressed the cheating rumours on the Call Her Daddy podcast in a rare long interview.
"It's about people knowing the truth, because there's a truth," she said.
"There is a lot I have avoided speaking on for a long time. This is so crazy, I have never talked about this ever."
When asked directly if she'd had a romantic relationship with her now-husband at the time he was with his former partner, Hailey responded bluntly.
"No, not one time," she said.
"He was not in a relationship ever, at any point.
"It's not my character to mess with someone's relationship – I would just never do that. I was raised better than that. I'm not interested in doing that and I never was.
"Period, point, blank."
Hailey went on to explain how rumours surrounding their "young" engagement were fuelled by a lack of public knowledge about the real timeline of their relationship.
"The only people who know the truth of what went down are me and him," she said to Cooper.
"I understand how it looks from the outside. We were really young, when we got engaged – I was 21 he was 24. I personally thought I wouldn't be getting married that young.
"The timing was very rapid. It felt correct at the time."
Hailey was then pressed on Justin's final split from Selena, describing it as a "healthy, mature decision".
"It closed a chapter and I think it was the best thing that could have happened for him to move on," she said.
"I know the reason we were able to get back together was because it was completely closed."
Hailey also revealed she had spoken with Selena since the wedding, declaring "there is no drama personally," and that the discussion had brought her "a lot of peace".
"She [Gomez] doesn't owe me anything," she said.
"I respect her a lot."
