Sources with direct knowledge tell TMZ there's good reason Margot's emotions came pouring out that day. We're told Cara's been struggling for a while now, initially with mental health issues, but now the people closest to her believe she needs rehab too.
We're told Margot and other friends are advocating for Cara to immediately get into a treatment program that includes mental therapy as well as substance abuse treatment.
You might recall, Cara and Margot went on vacay together in August ... traveling to Spain with other friends to celebrate Cara's 30th birthday, and since then she's appeared increasingly erratic in public.
Last week, she looked totally disheveled and seemed confused after initially boarding one of Jay-Z's private jets in Los Angeles. The flight never took off, and she got off it 45 minutes later.