Joely Richardson has revealed a long-running relationship needs a lot of work.
The actress, who is divorced from film producer Tim Bevan, admitted it's not always easy keeping the sparks alive in a romance over the years.
"I think long-term relationships are trickier. Most people say long-term marriages are the hardest thing," she said.
The 49-year-old, who stars in romantic drama Endless Love alongside Alex Pettyfer, heaped praise on her co-star Bruce Greenwood, who has been married to Susan Devlin for over 28 years.
" Bruce is wonderful because he loves his wife so much and he talks about her all the time, in the most glowing terms. I love that," she added.
Joely - who has dated Jamie Theakston and Archie Stirling - revealed her past relationships haven't disillusioned her about love.
"I suppose I am much more of a poetic. I totally believe in love and I believe in fighting for it," she said.
"Love, whenever it happens, is sort of like a battery - it never stops. So whether you're 17, 25, 35 or 45, it always has that same power. It's still like being hit by a bus. All reason goes out of the window."
:: Endless Love is in cinemas now.