Justin Bieber has said he struggled with the idea of commitment and faithfulness before proposing to his now wife Hailey Bieber.

Speaking on the special birthday edition of The Ellen Show, which is set to air today, the 25-year-old singer opened up about popping the question to the 23-year-old model.

"I was extremely nervous. I felt like in the past, we had talked about you know, me asking the question, and I felt like she would say yes," he told Ellen.

"So I wasn't really nervous about the saying yes, but I think I was more nervous about 'Am I gonna make this commitment? Am I able to make this commitment as a man and be able to honour you know, what I say?'"

"You know because that’s a serious commitment, when you say you’re gonna love someone for better or for worse and like, be faithful."

"That's huge. Am I able to do that? And so I think that was really what I was battling with."

"And I finally was like, 'You know what? I’m gonna make the decision and follow through with it. Be a husband, and you know, this is what I’ve always wanted. I’m gonna just choose this woman and just do it.'"

The couple married in secret in New York last September but chose to exchange vows a second time to mark their first anniversary with friends and family at a ceremony in the Somerset Chapel in South Carolina in October.

Earlier in the month Bieber told his followers on social media that he had been diagnosed with Lyme disease - a bacterial infection spread by ticks - and glandular fever.