Gwyneth Paltrow has been offering advice on relationships.
The actress - who is married to Coldplay singer Chris Martin, was previously engaged to Brad Pitt and dated Ben Affleck - compiled tips from experts to help people survive the "ever-evolving organism" of their romances.
She wrote in her GOOP newsletter: "A long-term relationship between two people is an ever-evolving organism. Some stay the course, some fall, all stumble.
"I asked a few very wise women, most of whom are in varying forms of long-time partnerships, for their insights."
One expert who offered tips was Monica Berg, creative director at the Kabbalah centre in Los Angeles, who claimed marriages need constant work.
She said "There are no stable marriages. There may be happy ones, but not stable ones. Either we are growing forward or falling backwards. This is true in all areas of our life... which is why I believe nurturing relationships is so important.
"We owe it to ourselves and those we love not to settle for mediocrity in anyway, and instead to nurture and allow our relationships to become the source of joy, support and love that they were intended to be."
Earlier this year, Gwyneth and Chris dismissed speculation their marriage was in trouble after they weren't seen together for several months.
Chris said: "One week you are divorced, the next week your band has broken up. It's terrible. I'm glad I'm not me. All I can tell you is that. It is news to me."
When asked why the couple rarely appear in public together, 31-year-old Chris said: "It is just the way it feels best."
Despite their denials, Gwyneth - who has a five-year-old daughter Apple and three-year-old son Moses with Chris - has admitted her marriage has "issues".
The 'Iron Man' actress, who made a pact with the musician to never discuss their private life, said: "Nothing is as good as it looks. Life is complicated, and there are always issues to overcome. One day he goes to Australia, and I go somewhere else - you have to accept that.
"He is going to kill me for talking about this!"