"On set, I was like 'Oh yeah, we're totally going to date,' and I would try to flirt with him, which ended up looking like I had something in my eye," Roberts, 22, told Chelsea Handler on Wednesday night's Chelsea Lately. "He literally didn't speak to me the entire movie, like thought I was so weird."
She fully understands why Peters didn't return her affection at first.
"I have no makeup on, it looks like I cut my own hair off," she said of her Adult World character, a wannabe poet who works at an adult bookstore. "I was not exactly looking cute to get a man."
Eventually, her crush turned into something more. Peters, 27, started texting Roberts, and she was asked to join the third season of American Horror Story, which Peters has worked on since the beginning. Rumors that the two were dating first circulated in the summer of 2012. Earlier this month, PEOPLE confirmed their engagement.
The Coven finale aired Wednesday night, but fans can still see Roberts and Peters in action. Adult World opens in limited release Feb. 14, making Valentine's Day extra sweet for the real-life couple.