"Nothing dramatic happened. They are friends and will continue to parent their son together. They have been friends for years and are happier this way than being married," the source says.
The couple welcomed a son last July, and he became the focus, the source adds. "Evan loves being a mom. After her son was born, he has been her No. 1 priority. The marriage always came in second. They have different goals for the future and want to pursue them separately."
As for Wood's romantic future, the source adds: "Evan is very edgy and adventurous and wants to find a partner that she can share that with."
For now, as she copes with the breakup, Wood, 26, is leaning on her friends – among them, Ellen Page. The two are BFFs and will play sisters in the upcoming film Into the Forest.
On May 20, the former True Blood actress joined Page and a group of buddies, including Sara Gilbert and Linda Perry, for a night of live music at the Sayers Club in Los Angeles. They were seated next to Demi Moore, who was there to watch her daughter Rumer Willis perform.
"Evan seemed like she was in a good mood," an onlooker tells PEOPLE. "She was laughing and talking to the group about wanting to sing at Sayers sometime soon."
Wood spent Memorial Day weekend with designer Phoebe Dahl and model and deejay Ruby Rose at their home in L.A. Wood relaxed by playing with the engaged couple's pet pig Hazel. The three also hung out together at the L.A. Gay & Lesbian Center's "An Evening with Women" charity event in Beverly Hills on May 10.
Meanwhile, Bell, 28, was last seen in Louisiana on May 14 filming the reboot of the new Fantastic Four movie. He plays the Thing.
Reporting by MELODY CHIU