"Everybody I've dated I've been sexually attracted to immediately," the star of the new biopic Lovelace tells ELLE for its August issue, on newsstands July 23.
"Sparks don't grow – your vagina doesn't become more inclined to wanting someone just because you're around them."
Onscreen, Seyfried, 27, plays the victimized adult star who became a household name in the '70s on account of her X-rated movie Deep Throat.
As for Lovelace", which opens Aug. 9 – and originally was to have starred Lindsay Lohan, whose ongoing personal problems likely cost her the role – Seyfried says, "I read the script and I was like, 'Wow, this is the riskiest thing that's happening [in Hollywood] right now.' "
Regarding any potential personal risks that might involve her, Seyfried says, "The first thing you think about is that it could have ruined my career. At the same time, I was like, 'This is my chance to show them, to show the industry, to be recognized.' "
In her personal life, although Seyfried says she and ex-boyfriend Dominic Cooper will always love each other, she admits that she has moved on to someone else.
"[He's] someone separate from my industry life. I've known him since he was 16 … I picture him as the father of my children all the time. But it is a fantasy right now."
Carter Smith for ELLE