In October 2016, Prepon's former That '70s Show co-star and close friend Ashton Kutcher revealed just how private the actress is when it comes to her personal life.
"I'm very upset with her right now. She just announced this engagement, and I had to find out in the news! She's my friend," Kutcher told Kelly Ripa during his appearance on Live With Kelly. "By the way, it's not just a random engagement. It's an engagement to another friend of mine!"