Holly Willoughby is said to have been forced to employ "acting skills she didn't know she had" to navigate the split from Phillip Schofield "amicably".
Long-standing presenter Phil, 61, left This Morning with immediate effect over the weekend amid a rumoured 'feud' with co-star of 13 years Holly.
The pair were said to have been "barely speaking" off camera during the past few weeks.
Following Phil's shock announcement, an ITV Spokesperson confirmed: "Phillip Schofield’s decision to step down from This Morning was (as his statement made clear) a decision agreed between Phillip and ITV."
However, the move has been called Holly's "worst nightmare" as the issues are now playing out in public.
"It's been the week from hell and has required acting skills Holly never knew she had," a source told Heat Magazine.
"Despite everything that is going on, and all the screaming and shouting, she is staying firm on wanting an amicable split.
"All she wants is for this to be over and not go nuclear," they added.
It has since been reported trouble between Holly and Phil could have kicked off long before rumours of a feud even emerged.
Things could have taken a turn in their seemingly unbreakable friendship after Phillip reportedly 'destroyed Holly's plans for a big change on This Morning'.
Phillip is said to have gone over Holly's head on the show after she requested an all-female cast and crew for International Women's Day.
Back in March, Holly along with the show's editor Martin Frizell, had reportedly decided that an all-female presenting line-up would be the perfect way to celebrate the mark annual Women's Day.
However, Phillip was reportedly not one bit happy with the idea of being pushed aside, and instead, went over Holly's head over the matter.
The This Morning presenter, "went to ITV's big boss Emma Gormley to put a stop to them", according to Mail Online.
In the end, after Phillip reportedly "put his foot down", Holly was only allowed to host the first section of the show surrounded by the show's female production staff while Phillip took some time away from the This Morning set to have a coffee "down the road".
Speaking to the publication, and insider claimed: "Holly was livid about Gormley's decision and the fact Phillip had undermined her, and made that very clear to numerous people at ITV.
"It was the first real sign to This Morning staff that their relationship had fractured and Holly wanted to step out of Phillip's shadow."
Announcing his departure, Phil said: "I have always been proud to cover fascinating stories on This Morning. But recently, This Morning itself has become the story.
"Throughout my career in TV – including the very difficult last few days – I have always done my best to be honourable and kind.
"I understand that ITV has decided the current situation can’t go on and I want to do what I can to protect the show that I love.
"So I have agreed to step down from This Morning with immediate effect, in the hope that the show can move forward to a bright future."
