However, he was surprised when the result came back positive, they added.
Representatives for Andre confirmed to the Daily Mail that he had contracted the disease but said he was recovering and “coping well”.
The Sun’s source said that because MacDonagh is out working on the frontline, “Pete has no option but to look after his four children as normal and isolate away from Emily at home”.
They said that there was “no-one else” who could look after the children “and he doesn’t want to put anyone else at risk of catching it.”
Andre and MacDonagh have two children together – Amelia, seven, and Theo, four. The 47-year-old’s older children – Princess, 13, and Junior, 15 – from his previous relationship with Katy Price also live with them.
Thursday, the day that Andre’s diagnosis was revealed, was also Amelia’s seventh Birthday.
In a post, which made no mention of his health struggles, the proud dad wrote: “Happy 7th birthday to my beautiful, kind and incredibly clever daughter Amelia. Love you to the moon and back .....and back.
“It's going be a quiet one but still as special as ever even if it’s distanced ps thank you to @tofclass_ for delivering our balloons at such short notice. Amazing.”
Watch: Peter Andre has tested positive for coronavirus
MacDonagh previously revealed that she had tested positive for Covid-19 back in June.
She told the Sun of her heartbreak at being banned from hugging her children as she was forced to isolate away from her family at their Surrey home.
Emily, 30, said: “I was only able to wave at them from the top of the stairs. Myself and Pete also slept in separate bedrooms just to be on the safe side.
“It was horrible but the family adapted to it really well and I got a big hug at the end. I had a sore throat and lost my sense of smell and taste for a week.”
Watch: Peter Andre heartbroken as he hasn't hugged son Junior 'in so long' due to COVID-19