The Bathgate-born star, 49, who played the 10th Doctor, wed Georgia – who is the daughter of fifth Doctor Peter Davison – in 2011.
Georgia, 35, told That Gaby Roslin Podcast that she instigated the relationship.
“I very much forced it into happening,” she said.
"I was very much the driving force. Had I not worked quite so hard, it might not have happened.”
She told her husband during the podcast, which they recorded together: “You couldn’t quite believe that’s why I was messaging you 400 times a day.
“You thought maybe I was lonely and wanted a chat… I very much fell into stalker category. Thank goodness I did though. I just made a decision, I thought, ‘This is going to be good, let’s do this, I’ll just persevere until he gives in.'”
Tennant, who has five children with Georgia, said: “I thought we were an unlikely life partnership, there was a bit of an age gap.
“Because Doctor Who had run through my life like a stick of rock, to end up marrying the daughter of one of the doctors, it all felt a bit stupid… so there were a lot of things against it.”
But Des star Tennant also said it was “fortuitous” the pair had met.
He added: “There’s a great Tim Minchin song, ‘If I didn’t have you someone else would probably do’… but I certainly feel like I lucked out.
“You reach a point of your life when you’re looking for someone and it’s sort of chance which version of that perfect partner ambles along.”
Peter Davison famously played the fifth incarnation of the Timelord between 1981 and 1984.
Tennant met his future wife when she appeared as the Doctor’s cloned daughter in the 2008 episode The Doctor’s Daughter.
Their fifth child, Birdie, was born last October.
Georgia spoke of the difficult time last year when their infant was taken to hospital as her husband filmed Des.
“At the beginning we were a bit like, ‘She’s fine, it’s like a bit of a cold, it’s not a problem’,” she said.
“Within 24 hours it was, ‘No we’re not fine. It’s a bit more serious,’ within three days we got into intensive care…
“But because our NHS is amazing they saved her and we got to go home again.
“I remember the doctor saying… ‘The hard bit is when you go home because people go, the baby’s fine, they move on, and… there was a period of time when we didn’t think we were going to have her anymore… That lasts for a really long time.
“Our baby still shares our bed because I’m sure I still make that happen… that her breathing is fine and that everything is going to be OK.”
That Gaby Roslin Podcast is now available on Apple Podcasts, Spotify and all podcast streaming platforms. Episodes are weekly, released every Monday.