Actress Amanda Seyfried has said that she is not sure if her boyfriend is "the one".

The 24-year-old actress is dating her 'Mamma Mia!' co-star Dominic Cooper.

Speaking to Teen Vogue the 'Letters to Juliet' and 'Dear John' actress said "A lot of people ask me, 'Is Dominic the one?' I don't know, and I'm fine with that." She added that planning too far ahead can lead to "heartbreak".

She continued "Love is great and possible always, but it's very rare to have the feeling that 'I want to be with this person forever.' "