Actress Sandra Bullock and her Proposal co-star, Ryan Reynolds, have reportedly been secretly dating for several weeks.

The close friends and co-stars have been rumoured to be dating on several occasions, and were spotted just last weekend holidaying together in Wyoming with Sandra's son Louis.

"They're crazy about each other," a source told Now magazine. "It's amazing to see Sandra learn to trust a man again."

Last year, Bullock divorced West Coast Choppers CEO, Jesse James after reports of his infidelity surfaced. Reynolds also officially divorced from actress Scarlett Johansson in July.

Reynolds and Bullock are expected to re-unite on the big screen as they lead the voice cast of And Then There Was Gordon, an animated comedy from Reynolds and Allan Loeb's recently launched TV company DarkFire.