The Hitch actress has been dating filmmaker George Augusto since 2...
And Mendes insists the tradition of marriage is no longer relevant.
She says, "I just don't think marriage is necessary, as necessary as society makes it. And I don't have a negative point of view on it. I just think it's a very old tradition and if you look back to what marriage symbolises in the first place... it has nothing to do with why we get married today.
"I don't know if I want children, but the idea of marriage sounds very boring to me. I have to be honest... I am extremely romantic but I think there is that little rebel inside me that is anti-establishment. It's just one more fun thing I can rebel against."