Is Supermodel's Soon-To-Be Ex a Sex Addict?

"For sex addicts, the only way they know how to get an erection is by imagining the porn stars [they've become attached to]," added Weiss.

Weiss, who said that some sex addicts are predisposed to the condition because of neglectful childhoods or abusive relationships, said that hiding this behavior from unsuspecting spouses really isn't that difficult.

"A lot of women, since they don't watch pornography and have never had the neurological fantasy with porn, have no concern about it," said Weiss. "They have this sort of naivete about pornography."

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But sex expert and author of "The Complete Idiot's Guide to a Healthy Relationship" Judy Kuriansky said that not all avid porn watchers are sex addicts.

"The criteria for a sex addiction is two-fold," said Kuriansky. "You have to not be able to control your impulses and also get into trouble because of what you're doing."

Sexologist Logan Levkoff agrees.

"Sex addiction has always been a tricky subject because there is a debate about whether or not it even exists," said Levkoff.

"As for Cook's activities, while I don't know enough about him to label this an 'addiction', there are definitely some compulsive elements to this," Levkoff added.

A lot of what Cook admits to doing behind Brinkley's back, Kurainsky added, signifies low self-esteem and extreme narcissism that is seen in many men who get wrapped up in their reputation.

"[Having an affair] with a younger girl is part of what a lot of guys do when they're in a relationship with a powerful woman and they're feeling threatened," said Kurainsky. "They can do anything they want and exert power over the younger girls."

Spending large sums of money – whether on the younger girl or on pornography – is another ego-booster, said Kurainsky.

"These are men who have wealth and fame and opportunity and huge sex drives," said Kurainsky.

"Those impulses make them do things that they think they can get away with," she added.