The 30-year-old actress and 27-year-old reality star dated for two years before they broke up in 2009. The pair shared a close relationship, and Rob appeared to be devastated on Keeping Up With the Kardashians when his attempts to win Adrienne back failed.
Now, Adrienne says that she has "no idea" how Rob is doing. The actress spoke to Us Weekly at the Gordon Parks Foundation Awards Dinner on Tuesday, and said she doesn't "know anything" about her ex or his absence from Kim and Kanye's wedding.
Kardashian family friend Jonathan Cheban reportedly spoke to Adrienne at the 2014 Fresh Air Fund Gala last week, and urged her to reach out to Rob.
"Their conversation was intense and serious," a source tells the magazine. "Jonathan was telling Adrienne she should reach out... He seemed concerned for [Rob]."
"Adrienne looked really sad," the person continues. "She was shaking her head, as if she didn't know what to do or say about the whole thing."
Rob has struggled with his weight in recent years, and skipped out on sister Kim's wedding for unconfirmed reasons. Sisters Kendall and Kylie Jenner appeared on Good Morning America on Tuesday, and told host Amy Robach their brother is "doing really well."
Celebrity Families of 2014 [PHOTOS]