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Real Housewives of Beverly Hills stars Adrienne Maloof and husband Paul Nassif are separating after nine years of marriage together.

Paul officially filed for legal separation from Adrienne in L.A. County Superior Court Monday morning.

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According to Adrienne, the longtime couple's three children were a big reason for the split.

"I'm so sorry that this is happening but my children are my life and sometimes we need to do what's best for them," she tells RadarOnline.com. "It's an unfortunate situation but, I have to have my kids' best interest at heart."

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Adrienne and Paul, a plastic surgeon who's appeared on E!'s Dr. 90210, have three sons together -- Gavin and twins Colin and Christian. The couple wed in 2002.