Hugh Hefner doesn't believe in sex addiction.

The Playboy magazine founder - who has famously enjoyed relationships with multiple girlfriends at the same time - claims the condition is just a "cop out" excuse for adultery.

He said: "I think by and large it's a cop out. I think 'sex addiction' is a convenient phrase for what is really an obsession. Sex is not like a drug or alcohol. It doesn't affect the physicality in the same way. But it can become very obsessive. Neurotic people can do very foolish things. People make choices. Most people who cheat do it because they think they can get away with it."

Hugh, 84, recently revealed he had parted ways with twin girlfriends Kristina and Karissa Shannon because his relationship with 23-year-old Crystal Harris is getting serious.

The media mogul - who has been wed twice - admits he is focusing all his energies on making Crystal happy, but is worried if they ever decide to marry, their relationship will change.

He added to "I think the most important component of a relationship is honesty and paying attention to the person - what your mate has in mind and what they really want and need. You have to find ways to make it fresh. For example, tonight I am taking Crystal and a couple of her girlfriends out to see 'Alice In Wonderland'. That isn't something I would do on my own, but I'm doing it for my girl because I love her and I want to keep her happy because she keeps me happy.

"I'm a romantic and I'm in a very good relationship with Crystal, and I want to keep that as it is. If that requires marriage, then I may get married. But my own inclination is to try to keep the relationship as it is now."