Cindy Crawford's husband Rande Gerber has been friends with George Clooney for 20 years, giving the supermodel a front-row seat when it comes to the Oscar winner's romantic life, so ET asked Crawford how Clooney has changed since settling down with wife Amal.

"George has always been a great guy, but he's definitely a happy guy now," Crawford told ET while promoting her new book, Becoming, out Tuesday. "Maybe he's happier. It just feels so comfortable to him."

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The Clooneys celebrated their first full year of marriage on Sept. 27. One might think that being married to a global superstar might require some lessons in how to deal with prying paparazzi, but according to Crawford, Amal does just fine on her own.

"She just handles it so well, I don't think she needs my advice on anything," Crawford said.

While the Clooneys have barely gotten off the starting blocks in their relationship, Crawford and Gerber have 17 years of marriage to look back over.

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"I think the secret to our relationship is that we were friends first," Crawford said. "We really like each other. Even when we get mad at each other we still treat each other with respect."

In Crawford's new book, she chronicles her life and career via stories and some of her most memorable images.

Watch the video for more.