EXCLUSIVE: Lisa Vanderpump Is 'Deeply Saddened' by Yolanda Foster's Divorce, Admits She 'Hadn't Seen the Signs

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Even though the lives of a Real Housewife are broadcast for the world to see, Yolanda Foster's divorce was still a shock to many -- including her Bravo co-stars.

"I hadn't seen signs," Lisa Vanderpump told ET at the premiere for the new season of Real Housewives of Beverly Hills. "For me, I was completely shocked and deeply saddened by it."

The Los Angeles restaurateur revealed that she still doesn’t know "the whole story" behind Foster's split.

EXCLUSIVE: Yolanda Foster Says She's 'Heartbroken' Following Split From Husband

"You expect on a reality show that you're seeing what's going on in somebody's life," she said. "When I heard that and was told, I said, 'That's absolutely nonsense, absolute rubbish. I don't believe that for a second.' So when I found out it was true, [I was] deeply saddened."

"It absolutely shocked me," she stressed. "It really did shock me. I just hope she's on a path to recovery. She's been through a lot."

After four years of marriage, Yolonda and David Foster announced their split earlier this week. Yolanda, who has been battling a devastating case of Lyme disease since first being diagnosed in 2012, admitted to ET that she and her ex had been growing apart in recent years.

"We really loved to see them together," Lisa said. "I thought they were a really kind of lovely, glamorous couple that seemed to have a deep love. So I don't kind of understand."

WATCH: Yolanda Foster Speaks Out About Divorce: 'Don't Judge Our Journey'

When asked if filming the hit Bravo series ever affected Lisa's relationship with her husband, Ken Todd, the brunette beauty was candid with her response.

"Ken and I have been together 33 years," she said. "I think the dynamic can change in a relationship when the woman suddenly is thrust into the spotlight. We were always very equal because we were partners in business. In one way, I think It made it stronger."

"I hope they manage to figure things out," Lisa added of Yolanda's divorce. "I would love to see them together. I'm biased, but I think they were great together."

Press play on our exclusive interview with Yolanda Foster below to get the details on how she and David "grew apart" over the years.