The Dark Knight star wed the actor last year (09) after seven years of dating and they share a three-year-old daughter, Ramona.
Gyllenhaal often accompanies her husband on movie shoots and she loves nothing more than tidying his trailer while he works.
The actress also credits her Nanny McPhee and The Big Bang co-star Emma Thompson with giving her a "classical" outlook on her partnership with Sarsgaard.
She tells America's Good Housekeeping magazine, "Emma, you kind of gave me the idea that a part of my life, a part of my mind, has to be devoted to my husband. My mother's generation has been bucking against that.
"But I've just been finding so much pleasure in sacrificing sometimes for my husband - going to where he's working and tidying up his trailer because he couldn't manage to do it, and bringing him things that will make him feel better, and being a wife in a more classical way. It feels really right to me."