Carrie Symonds was heavily pregnant when her fiance Boris Johnson was taken into hospital with coronavirus, and she was also battling the illness herself.
A friend said she was "distraught" and "in tears" when the Prime Minister was moved to the intensive care unit at St Thomas's in Westminster.
According to insiders, the disease hit Johnson "like a sledgehammer" despite his efforts to put on a brave face.
Strict coronavirus social distancing rules meant Carrie wasn't allowed to be by his side as he battled the disease, so she had to come up with another way to keep his spirits up.
Carrie sent Johnson daily updates and ultrasound pictures of their unborn child to get him through the awful time.
A source told the Sun : “It’s been a very, very worrying time for Carrie.
"She has been urging Boris to get well for their unborn child.”
When Johnson was admitted to hospital the couple hadn't seen each other for more than a month over concerns for Carrie, who was isolating while pregnant.
Boris, 55, used the time off to watch his favourite movies - including Withnail and I and JRR Tolkien’s Lord of the Rings trilogy.
He is also reported to have finally watched Love Actually.
After six days in hospital he was discharged and moved to Chequers to continue his recovery.
However he's now back in London and has returned to work.
After leaving hospital he released a video saying NHS staff "saved my life - no question".
He also admitted "things could have gone either way" when he was taken to intensive care.
When he returned home Carrie took to Twitter to thank the NHS for looking after him, saying parts of the week had been "very dark indeed".
Tweeting a rainbow emoji, the 32-year-old wrote: "I cannot thank our magnificent NHS enough.
"The staff at St Thomas’ Hospital have been incredible. I will never, ever be able to repay you and I will never stop thanking you.
"There were times last week that were very dark indeed. My heart goes out to all those in similar situations, worried sick about their loved ones.
"Thank you also to everyone who sent such kind messages of support. Today I’m feeling incredibly lucky."
