It's considered a faux pas in the world of romance, but a rising number of celebrity couples are either hinting at or admitting to having an open relationship.

View our gallery of celebrities in open relationships here.

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Tilda Swinton and her long-time partner, John Byrne are perhaps the most vocal stars to talk of their unconventional love life, with both regularly appearing on red carpets with their girlfriends or boyfriends in tow.

In fact, despite having twins together, they have an intriguing menage a trois style arrangement with Swinton's toy-boy, Sandro Kopp, who even resides at their Scottish home.

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