The 38-year-old actress confessed that they have their fair share of ups and downs and said she has no way of predicting how their relationship will work out.
“Sometimes it’s hard being with someone for a long time,” she says in the September issue of Elle magazine.
Talking about her marriage to Martin, who she wed in 2003, the Country Strong star says: “We go through periods that aren’t all rosy. I always say, life is long and you never know what’s going to happen.”
Paltrow, who has two children with the Coldplay frontman, also sang his praises as a father.
“If, God forbid, we were ever not to be together, I respect him so much as the father of my children,” she says.
“I made such a good choice. He’s such a good dad. You can never be relaxed and smug and think ‘I’ve got this thing’.”
She adds: “That’s also part of it – keeping yourself on your toes. I’m not going to take this for granted.”