The Oscar-winning actress has been wed to Coldplay frontman Chris Martin for seven years and while she insists the pair are still happy together, she admits married life is not always easy.
Gwyneth - who has two children, Apple, seven, and five-year-old Moses, with Chris - said: "Sometimes it`s hard being with someone for a long time. We go through periods that aren`t all rosy. I always say, life is long and you never know what`s going to happen."
And while the 38-year-old beauty says they have no intention to split up, she knows if they ever did it would be amicable because they have a lot of respect for each other.
She told America`s Elle magazine: "If, God forbid, we were ever not to be together, I respect him so much as the father of my children.
"I made such a good choice. He`s such a good dad. You can never be relaxed or smug and think, `I`ve got this thing.`
"That`s also part of it: keeping yourself on your toes. I`m not going to take this for granted."