Joshua, the former two-time world heavyweight champion, has not fought since his defeat in the rematch against WBA, IBF, WBO and IBO title-holder Oleksandr Usyk in Saudi Arabia in August.
Joshua, 33, had been hoping to take on Tyson Fury in a money-spinning, all-British clash in the UK in December, with the undefeated WBC champion prolific last month on social media, demanding certain dates for the contest and repeatedly setting different deadlines for Joshua to accept.
In the end, Fury signed to defend his title in a trilogy bout with Derek Chisora in London next month.
On Saturday, Joshua was in Abu Dhabi at the capital’s inaugural Champion Series event, and told reporters that he had been thinking initially about taking a year off from the sport.
However, Hearn later said: “He was just [annoyed]. He got his bluff called really, we feel, and he accepted. And he just lost faith a little bit with boxing. Because he really wanted to fight Tyson Fury.
“That’s the main reason he didn’t fight this year. It messed up his mojo, and made him think, ‘What are these people doing? They say they want to fight me, Chisora gets another month to do the deal when I had to sign it then, etc’.
“That’s why you’re going to see him maybe end of February, but probably March. We were going through opponents tonight and I think he’s now going to have the rest of the year off and start camp in January.”
Anthony Joshua v Oleksandr Usyk - in pictures
Hearn listed a selection of heavyweights in play for Joshua’s comeback, including Otto Wallin, Filip Hrgovic, or even a rematch with Dillian Whyte. Joshua defeated his compatriot by knockout in 2015.
“I think the winner of Dillian Whyte against Jermaine Franklin [on November 26] is a very, very good front-runner for the next fight.”
On a possible bout against former WBC champion Wilder later in the year, Hearn added: “Definitely. He was one of the names I mentioned to [Joshua] tonight. He just wants to fight everybody. It’s just a case of, not an easy fight, but an easier fight, before he goes into a Deontay Wilder or maybe a Dillian Whyte.”
Saturday’s event at Etihad Arena marked the first in the multiyear partnership announced in August between Abu Dhabi and Matchroom Boxing.
Hearn, who told The National earlier this week he planned as many as four events in the emirate next year, said of their inaugural show: “Really good, a big learning experience. Don’t forget when the UFC came here, I think 10 years ago, it took a long time to get to where they are now.
“And that was the first boxing event here. It was good card, nice crowd, good atmosphere. And people learning about the sport. Looking forward to being back in spring.”
Asked how close Matchroom are to deciding on that line-up, Hearn said: “We’re just going to look at which fight we’ll bring here now. And that’ll happen over the next couple of weeks. We’ll be back for the Formula One, it looks like, to have meetings and move forward with the next one.”