Blythe said: "I've never seen two happier parents and people. Happy, happy people. I don't get it."
Blythe also quashed rumours Gwyneth is planning to quit Hollywood and focus on raising the couple's two children, three-year-old daughter Apple and one-year-old son Moses.
The 'Meet the Parents' star said: "People are saying Gwyneth isn't going to go back to work, which is a lot of BS too. She very much wants to go back to work.
"She's a great, wonderful actress. But motherhood is very important to her, as it was to me, and she's finding the balance. And it's hard to find that balance."
The couple have been spending a lot of time apart recently as Chris has been holed up in different recording studios working on the new Coldplay album 'Viva La Vida', while Gwyneth was busy filming new movie 'Iron Man'.