Top Gear host Paddy, 49, is said to be 'leaning on' TV presenter Kirsty, after his split with Christine, 34, last year, following 11 years of marriage.
At the end of February, Paddy was spotted 'getting cosy' with TV presenter Kirsty at the Ham Yard Hotel in London's Soho.
Kirsty split from her former rugby player Paul Sampson partner in 2015 after 16 years together.
Model and documentary star Christine is said to find the idea of Paddy dating a famous face like Kirsty "tough."
A source told Closer: "Even though Christine has been in a great place- she's moving on and knows it's through with Paddy- part of her is still getting over the end of her marriage, so hearing about him potentially being in a new relationship was naturally a surprise.
"The idea of Paddy dating a celebrity like Kirsty is also tough for her, just because she and Kirsty have some mutual friends and already people have been talking about it."
It was earlier reported that Paddy and Kirsty have been 'leaning on each other' since their break-ups.
"Paddy and Kirsty have known each other a long time and are good friends," a source revealed.
"They have a lot in common. They’re both single and have gone through marriage splits, Paddy more recently."
They continued to OK! Magazine: "Kirsty is a bit of a shoulder for him to lean on and she’s good at giving advice."
Kirsty recently revealed that she has been 'dating' but isn't in any serious relationships.
"I'm currently dating! I'm not with anyone in particular right now, but I'm very open to something," she told Closer magazine.
"That would be really lovely."
Christine, who shares three children with Paddy, previously admitted she feels 'petrified' over being a single parent.
She explained: "When I met my husband, that’s a time where I felt very safe and I wonder if that’s why I stayed in that relationship for 15 years."
She added: "We’re separated now and I know being a single woman, being a single parent is an extremely vulnerable place to be and it absolutely petrifies me, but that’s life."
Speaking to OK! ahead of the release of her documentary, Christine McGuinness: Unmasking my Autism, Christine said: "Dating was never on my mind when I was filming the documentary. Really not. But I think watching it, hopefully, you know, people will understand why.
The Games star also says she's not ready to date.
"I think most people will was expect somebody who's just come out of a long relationship to maybe be really excited about dating. But it's just not something I thinking about.
Christine shares three twins Penelope and Leo, both nine, and seven-year-old Felicity with Paddy.
The Mirror has contacted Christine, Paddy and Kirsty for comment.