updated 04/30/2013 AT 8:00 AM ET
•originally published 04/30/2013 AT 10:15 AM ET
Catherine Zeta-Jones is hardly facing her latest health battle alone.
The actress’s husband of 12 years, Michael Douglas, is fully there for her as she enters treatment once again for her bipolar II disorder, friends say.
“He couldn’t be more supportive, just like she is of him. They’re solid,” a friend tells PEOPLE.
The friend adds: “They’re really, really devoted to each other.”
Douglas, 68, and Zeta-Jones, 43, stepped out together on April 22 in New York for the Film Society of Lincoln Center’s 40th Annual Chaplin Award Gala, honoring Barbra Streisand. They walked the red carpet together, and attended the tribute and a dinner afterwards. Fellow attendees said nothing seemed amiss.
“Catherine was on his [Michael’s] arm much of the time,” said one. “She seemed really relaxed and happy. I saw her with a cocktail and she was socializing and enjoying the evening Nothing seemed out of the ordinary, and they both seemed to be having a good time.”