Michael Atherton feels Kevin Pietersen ran out of allies in the England camp before making his decision to quit international cricket.
Pietersen was to be omitted from the England squad for a tour to the West Indies and the following Twenty20 World Cup in Bangladesh, decisions that led him to call time on representing his country.
While the South Africa-born batsman divided opinion for his attitude, he had plenty of supporters in the England dressing room, but former captain Atherton believes they had started to wane in recent months.
"It was coming, I think," Atherton told Sky Sports News. "There was a unanimity of views there from the people that count so ultimately I think Kevin Pietersen found himself friendless.
"He had no allies amongst the management, the hierarchy and the senior players as well because Paul Downton would have been taking soundings from them at the end of the Ashes tour.
"It was a pretty horrific Ashes tour and there have been a few victims along the way, but I think he just found himself friendless and with no allies.
"I think Alastair Cook is the interesting one (of the senior management) because he brought Pietersen back after the textgate during the South Africa series that led to Andrew Strauss' demise. I think that relationship has soured over the last few months.
"All these things are worse when you are losing. It's not always been sweetness and light where Kevin Pietersen has been concerned before but when you are winning these things are easier to keep a lid on.
"When it goes so badly all these little fissures and fractures below the surface come bubbling up and this has been the main one.
"Paul Downton said he wanted to regain team ethic and philosophy and reading between the lines they don't feel they can do that with Pietersen in the team.
"It's going to split opinion, probably more so in Pietersen's favour than not. There is a massive constituency of England supporters out there who love watching him play as I have down the years."
On Wednesday morning Pietersen wrote on Instagram, after posting a picture of his final Test in Sydney: "So sad that this will now be the last time I leave a field in an England shirt... Incredibly overwhelmed by the support overnight! Thank you so much..."
"I love England and I honestly hope they have every success in the future."
Pietersen played 104 Tests, 136 one-day internationals and 37 T20 internationals for England.
Speaking on Tuesday in a statement, Pietersen said: "Playing cricket for my country has been an honour. Every time I pulled on the England shirt was a moment of huge pride for me and that is something that will live with me forever.
"Although I am obviously very sad the incredible journey has come to an end, I'm also hugely proud of what we, as a team, have achieved over the past nine years.
"I feel extremely fortunate to have played at a time of great success for England cricket alongside some of the best cricketers the country has ever produced.
"I want to thank everyone for their fantastic support and I wish the team the very best of success going forward.
"I believe I have a great deal still to give as a cricketer. I will continue to play but deeply regret that it won't be for England."
You can watch a Sky Sports cricket special 'KP - The Great Innings' - on Thursday night at 8.30pm and also a 30 minute live show at noon on Sunday: 'KP - The Verdict' - both on Sky Sports 2HD. The shows will also be available via On Demand.