Williams wrote and directed The Dry Land, which stars Ferrera, who also executive produced. Based on war veterans affected by post-traumatic stress disorder (PTSD), the film "certainly is his baby, and I feel like I've been here to get to witness it," Ferrera told PEOPLE at last week's premiere of the movie in Los Angeles. "It's a little bit like he had the pregnancy and I'm holding his hand through Lamaze."
Meanwhile, their active work schedules have left the couple little time for wedding planning. "If there is a scale between 0 and 10, I'm at like negative 10," Ferrara says. "I haven't gone there and [am] not thinking about it. We got engaged and then left for Iraq the next day."
Ferrera, 26, and Williams are comfortable working together: In fact, their courtship began after he cast her in his student film at USC. "We kind of connected from the get-go on that professional level and that was something that really drew us to each other, a shared passion for what we do and our work," she says.
Although the pair kept business and pleasure separate on the Dry Land set, news of their upcoming nuptials wasn't a surprise to many. "They obviously love each other a lot," says costar Jason Ritter. "[When they got engaged] I was over the moon, thrilled, I love them."
Like their professional relationship, the wedding planning – when the time comes – will be a partnership. "We both talk about it," Ferrara adds. "It's so crazy because right now the only thing I'm sure of is that there will be a cake and music!"