Jul 3, 2008, 10:15 GMT
Scarlett Johansson says an open relationship would be "awful".
02/19/2008 - Scarlett Johansson - "The Other Boleyn Girl" Royal London Premiere - Red Carpet Arrivals - Odeon Leicester Square - London, England © Solarpix / PR Photos
The 'Lost in Translation' actress, who is engaged to actor Ryan Reynolds, previously claimed she doesn't believe people are monogamous but now insists she has always been faithful.
She said: "I believe in finding a soul mate. I've always been in monogamous relationships. I would never want to be in an open one. It would be too awful."
However, Scarlett did stand by her original view that being with one person can be difficult.
She added to America's Cosmopolitan magazine: "I don't think monogamy is a natural instinct for human beings.
"Monogamy can be hard work for some people. I don't think it applies to everybody, and I don't think a lot of people can do it."
The 23-year-old actress, who has previously dated Josh Hartnett and Jared Leto, believes love is a learning process.
She added: "You don't always meet the right person at the right time. It's important for people to figure out their own lives before involving someone else - to gauge where you are and work on your own issues."
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