Justin Bieber and his wife Hailey are a ''really strong unit'', according to his documentary director.

The 25-year-old singer and the 23-year-old model tied the knot in September 2018, and Michael Ratner - who helmed Justin's YouTube Originals series 'Justin Bieber: Seasons' - has said the pair are a ''fantastic'' couple.

Speaking about their bond, Michael said: ''I think they've got a fantastic relationship. I think that she's obviously a tremendous wife and they're working on being a really strong unit. I think he's working on being and is a great husband. It's a new relationship as far as marriage is concerned, but they seem excited about it, so it's really great. They're just working on making their marriage work and living as stable of a life you can while your life is very not normal ... It's a phenomenal two-way relationship.''

Justin is seen going through many hardships in the documentary series including a battle with drug addiction and his health, and Michael says the tough moments make his wedding feel ''so well earned''.

He added: ''It feels so well earned, you see his journey and you see such real happiness. I think that that episode makes a lot of people tear up. [When] we had the premiere, I don't think there was a dry eye in the audience.''

Michael also teased the upcoming series finale, which will show the emotional footage of the listening party Justin held before the release of his new album 'Changes', which dropped last week.

Speaking to 'Entertainment Tonight', he said: ''You're gonna see Justin's reaction and being able to see the world's reaction to the album,. Being able to see all that stuff is really quite cool and different.

''There's a moment when there's a lot of people ready to hear the music for the first time and you're sort of ready to let go of your baby. And we're just behind the scenes in the green room and he's just thanking some of his management team and then he goes out there and he seems nervous, just like anybody. He thanks the people and he broke down crying ... because I think he's filled with so much emotion and pride. It all sort of came together.''