"Spider-Man 2? star Andrew Garfield is not the kind of star who talks publicly about his real-life girlfriend and onscreen love Emma Stone, but now we know he may just be saving it all for a literary tome.

"I will write a book one day about how I feel about every aspect of Emily Stone," Garfield joked today on " Good Morning America," using the full name of his girlfriend of over two years.

Emma Stone Calls Andrew Garfield 'Incredibly Important'

"She's a full genius, or she has found her genius and she's doing it so beautifully," Garfield said. "I think everyone who works with her, everyone who brushes shoulders with her or even makes eye contact with her gets a shot of sunshine."

Stone, 25, and Garfield, 30, have been linked since 2011, around the time filming on "The Amazing Spider-Man" began.

In the movie's sequel, "The Amazing Spider-Man 2: Rise of Electro," opening Friday, Garfield's character, Peter Parker, confronts a relationship dilemma with girlfriend Gwen Stacey, played onscreen by Stone. Parker's life was one that Garfield says he related to more so than his alter ego, Spider-Man.

Inside the 'Spider-Man 2' NYC Premiere

"I think in life, what I find, is my biggest obstacle is myself and I think Peter Parker feels that way too because he's constantly in an existential dilemma," Garfield said. "There's something simpler about Spider-Man, definitely, because you're literally trying to neutralize any threat to any innocent bystander."

WATCH: 'Amazing Spider-man 2' Cast Takes Over 'GMA'

Garfield and Stone have been on a whirlwind tour premiering the movie around the globe and fielding reporters' questions. Today on "GMA," Garfield got not only a high-five but also a "zillion out of five" stars review from a 9-year-old reporter for Kidsday.

"Good question," Garfield said when asked by Newsday kid journalist Drew Hecht whether he did his own stunts. "I would like to say I do all my own stunts but that would be a lie. I do as many as I can but there are two amazing stunt-doubles."

Hecht also got Garfield to reveal he cried when he first learned he was cast as the new Spider-Man.

"I cried. I laughed, "Garfield said. "I got very scared. Very, very scared."