In the filing, which was submitted last week and first reported by TMZ on Tuesday, Armstrong cited "irreconcilable differences."
In a statement to PEOPLE on Tuesday, Armstrong said, "Ryne and I are taking some time apart to focus on ourselves and our children. While we are very sad, we are hoping that we will heal and be even stronger as a family. We ask for patience as we navigate this new chapter in our lives."
The RHOC star, 42, has asked for legal and physical custody of the pair's three children — twins Vera and Vince, 10, and Robert Valor, 9. She also offers Holliday visitation rights. Their official date of separation is listed as Sept. 8, 2021.
Just four days before the split went public, Armstrong, Holliday and their kids spent a day in Disneyland as a family. "What a ✨magical✨ day in Disneyland with the family!" she captioned a series of photos of the five.
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In March, Armstrong listed her Newport Beach home for $6 million. At the time, she confirmed she'd temporarily separated from Holliday prior to selling. "I'm just going to be honest. We actually separated," she told Page Six. "We separated and then lived life without each other."
The decision to move, though, was in hopes of a new beginning. "We are hoping our new home is a place for a clean slate and fresh start to work on our marriage and family," she added.
Stephen Ruiz - SRG Estates; Inset: Dr. Jen Armstrong/Instagram
Season 16 of RHOC outlined some of Armstrong's marital struggles. She's been open with the series, and host Andy Cohen, about the distance in her relationship with Holliday. After rewatching the season (which was Armstrong's first), she said her relationship had changed.
"We're becoming more equalized now, trying to work on our relationship and put more balance," she shared in part 2 of the season 16 reunion. "We're too far apart. I mean, obviously, you can see that we're, like, in different worlds."
Armstrong added, "It was interesting watching the show, because it was almost therapeutic to be like, s---, we've got to change this," Jen said. "This is just way too far, and we're both very unhappy."
In speaking about living separately, Armstrong explained that the time apart helped refresh their relationship. "He moved out for a little while, and it helped. It kind of reset," she said. "There was peace in the house. I was with the kids. It was actually really helpful."
Armstrong and Holliday did not immediately respond to PEOPLE's request for comment.