Ryan married actor Dennis Quaid on Valentine's Day in 1991, after starring in two films with him. It was during Ryan's engagement to Quaid that she had a falling out with her mother over his alleged drug abuse. Ryan agreed to marry him only after he kicked his drug and alcohol addiction. Quaid and Ryan have one child together, Jack Henry, born April 24, 1992. The couple divorced on July 16, 2001. Although Ryan had a relationship with actor Russell Crowe, with whom she made a movie, both she and Quaid deny it was a factor in their divorce. In a 2006 interview with Allure, Ryan indicated that Quaid had not been faithful to her during their marriage.
Ryan tends to support the U.S. Democratic Party, especially its environment protection programs and initiatives. In 2003, she supported General Wesley Clark's campaign for U.S. president. She supported John Kerry during the 2004 presidential elections