"I've been 'seen' with him," she coyly explained to the fashion magazine.
There have been conflciting reports about the two since they first me at a Halloween party hosted by Kate Hudson last October, but it appears that Seyfriend is ready to shed a little more light on her dating life.
The 25-year-old formerly dated "Mamma Mia!" co-star British actor Dominic Cooper, but that relationship ended once she discovered he was still seeing a previous girlfriend.
"I was just kind of foolishly thinking that the two of them were done and Dom and I were involved. But we weren't really as involved as I thought," she said. "So I got my heart broken pretty hard. And then it took a long time for us to break up again. After that, it's really hard to open myself up to a new person. Really hard."
Seyfried will be next be seen in the dark interpretation of the children's folk tale "Red Riding Hood," while Phillippe, 36, is set to star in the forthcoming "Lincoln Lawyer."