X Factor judge Louis Walsh has indicated that the One Direction lifestyle of travelling and touring constantly has meant the band have been living "in a bubble" for the past five years and said "something had to give."
Walsh told Irish radio station RTE Radio One:
"I have heard the rumours for the last few weeks that everything wasn't happy in paradise.
"The problem with these guys is they've been in a bubble for the last five years, pressure, working, a lot harder than people think, so something had to give. So Zayn was the first person just to crack up a little bit.
"He's had an amazing time with the other guys. That's the good side of it. The dark side of it is all the travelling, the airports, in a bubble, not really seeing real life."
Fellow former X-Factor boyband members have tweeted messages of support for Zayn Malik tonight after the One Direction star made the decision to quit the band.
Aston Merrygold, of JLS fame, and Union J's Josh Cuthbert both tweeted the star the "best of luck" following the announcement of his departure:
Counselling service ChildLine have warned that young people may be feeling "very distressed" after hearing the news that Zayn Malik has left boyband One Direction, and urged adults not to "undermine" these feelings.
Sue Minto, head of ChildLine, said: "There are young people who are going to feel seriously distressed at the news, and people are going to have to get their head around the fact that for some this will be very distressing and not to undermine it, even if they don't quite understand it."
She added: "Lots of people have pop stars or celebrities or actors who they hold in high esteem, and there is a lot of sadness and impact for people when something happens to any of them."
Anyone who is feeling distressed can contact ChildLine by calling 0800 11 11 or visit www.childline.org.uk.
Former X Factor judge Gary Barlow and McFly drummer Harry Judd have tweeted messages of support to the remaining members of One Direction, departing band member Zayn Malik, and the band's fans tonight.
The stars tweeted:
Bum out news for 1D fans ? Sad to see Zayn go but you gotta do what you gotta do. Brave decision
Malik, 22, first shot to fame after appearing on the X Factor in 2010, now five years after joining One Direction he is quitting the band.Read the full story ›
Simon Cowell, one of the X Factor judges who helped put together boyband One Direction, has said he is "truly sorry" to see bandmate Zayn Malik leave.
In a statement posted on the band's official Facebook page Cowell wrote:
"I would like to say thank you to Zayn for everything he has done for One Direction.
"Since I first met Zayn in 2010, I have grown very, very fond - and immensely proud - of him. I have seen him grow in confidence and I am truly sorry to see him leave.
"As for One Direction, fans can rest assured that Niall, Liam, Harry and Louis are hugely excited about the future of the band."
Zayn Malik has said that after five years in the spotlight it is "the right time" for him to leave boyband One Direction and commented in a Facebook post that he has "to do what feels right."
The 22-year-old's comments were posted on Facebook this afternoon as part of an official statement released by the band to confirm his departure.
"My life with One Direction has been more than I could ever have imagined. But, after five years, I feel like it is now the right time for me to leave the band.
"I'd like to apologise to the fans if I've let anyone down, but I have to do what feels right in my heart. I am leaving because I want to be a normal 22-year-old who is able to relax and have some private time out of the spotlight.
"I know I have four friends for life in Louis, Liam, Harry and Niall. I know they will continue to be the best band in the world."
Bradford-born singer Zayn Malik has left One Direction. Fans of the band have been tweeting their reaction.
@zaynmalik im not gunna say I won't miss you but im glad that you're putting yourself first. :) it's not gunna be the same without you.
One Direction have posted a statement on their official Facebook page today, confirming the departure of band mate Zayn Malik.
The statement said that "after five incredible years Zayn Malik has decided to leave" but that the other four members would continue as a band without him.
"We're really sad to see Zayn go, but we totally respect his decision and send him all our love for the future.
"The past five years have been beyond amazing, we've gone through so much together, so we will always be friends.
"The four of us will now continue. We're looking forward to recording the new album and seeing all the fans on the next stage of the world tour."
Zayn Malik has left One Direction, according to a statement released by the band today.