He said: "The hardest part was to compress all of that love, all of that joy into just one text message. And then it was just hitting send."
The actor also spoke about his "ridiculous" sex scenes with Sandra Bullock in 'The Proposal', admitting he is nervous about her husband Jesse James seeing the movie.
He added to US TV show 'Access Hollywood': "If I didn't know Sandra Bullock completely before, I do now. I know her in ways that her husband Jesse James would turn me into some sort of flying curd cottage cheese-type pudding if he knew. It's pretty incredible.
"It's actually ridiculous. Not only are you naked, you're doing a stunt as well. It's like expertly lit Cirque de Soleil porn."
However, Ryan insists he was comfortable with the intimate scenes because he and Sandra are such good friends.
He added: "She and I have known each other for eight or nine years, so we had this friendship already. The movie is kind of our chemistry in real life."
Despite being at ease with his co-star, Ryan took steps to ensure he looked good on camera.
Scarlett explained: "I was training for a marathon at the time, so that was my workout. I had to do these six or seven mile runs every morning. That was enough."