According to the latest reports, Ryan Donowho's latest long-term relationship was with actress Susan Highsmith. The pair dated for about four years before ending their relationship in 2007.
In the April 2006 issue of Nylon, the article mentioned Donowho's relationship with Highsmith.
...Donowho's girlfriend, Susan Highsmith. So what did Highsmith think of her 25-year-old man making out with a 14-year-old Willa Holland on The O.C.? "Yeah, she wasn't really into it," he says, laughing. "She thought it was gross."
Highsmith has been in a couple of movies with Donowho including The Pacific and Eddy.