The One Day actress said that Shulman "totally ruined" her plans to remain on her own when she fell in love with him.
She told Marie Claire: "I am very much in love. Adam totally ruined my plan. I was really actually looking forward to a little alone time and then I fall in love like a fool.
"It's three years. It's serious!"
Hathaway's ex-boyfriend Raffaello Follieri was imprisoned for four-and-a-half years in 2008 after pleading guilty to cheating investors out of millions of dollars, and the 28-year-old explained that she dealt with her heartache by joking about it.
She added: "That was how I got through my pain. I wrote funny songs about it. That's always been the way I deal with things. You make a joke of it."
Watch Anne Hathaway in the One Day featurette below: