Ariana Madix was shocked to find out that Scheana Marie's husband, Mike Shay, was dealing with substance abuse issues during Vanderpump Rules season four.

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In a new interview, Madix spoke of Scheana Marie and Mike Shay's marital troubles, which were brought on by his excessive drinking and substance abuse.

"There are some relationship issues between Scheana and [Michael] Shay; some issues with him personally," Madix told SheKnows on Tuesday of the fourth season. "Just different relationships and different friends are put to the test in a new way that people haven't seen before."

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Continuing on, Madix revealed she had no idea that her longtime friend was secretly suffering from issues with addiction, and her boyfriend and co-star, Tom Sandoval, was also caught off-guard.

"Scheana is one of my closest friends, but Mike Shay is one of my best friends, as well," Madix explained. "We've had a lot of conversations on our own, and I was like, 'Wow, that's not something that I ever thought was going on with him.' And I felt really horribly that he didn't feel comfortable talking to anybody it, and that he was kind of suffering through this alone. It bummed me out on a level that's hard to describe."

For more of Ariana Madix and Tom Sandoval, tune into Vanderpump Rules season four on Monday nights at 9 p.m. on Bravo.

Tags: Ariana madix Tom Sandoval vanderpump rules Bravo Reality TV Scheana marie mike shay