”People should know better than to be my boyfriend in the movies,” jokes Reese Witherspoon, after it’s pointed out that since her first film at 14, the coming-of-age drama The Man in the Moon, the objects of her affection have met with grisly farm accidents, psycho neighbors, and multiple shootings. This week Mark Wahlberg carries on the tradition as a young stud who terrorizes her in Fear.

Not that Witherspoon’s characters have anything to do with it; the Nashville-raised actress often plays sweet innocents. ”I’m a lot tougher,” she says, explaining that she accepted her role in Fear because she felt the story was relevant. ”I saw a lot of my girlfriends get into obsessive relationships as teenagers. The film shows people can make mistakes and they can be fatal.”

Witherspoon, 20, doesn’t seem the obsessive type herself, though she does admit to a ”bad” Jim Morrison fixation during which she slept below a six-foot poster of him. On the short list of young lead actresses (Alicia Silverstone, Claire Danes) who have already amassed impressive credits, Witherspoon has a resume that includes A Far Off Place, Jack the Bear, S.F.W., and Return to Lonesome Dove. She also enjoyed playing against type, as a high school girl looking for her mother, opposite Kiefer Sutherland in the thriller Freeway (opening theatrically this month after debuting on HBO). ”Her character’s still a kid but also quite ruthless,” says director Matthew Bright. ”I don’t think there’s anything she couldn’t do.”

The daughter of a physician and a nurse, Witherspoon is a self-described debutante, having participated in what she calls ”some sort of paganistic virgin ceremony where you wear a white dress.” She is paying her own way as an English lit major (though she may change to premed) at Stanford. And she just filmed Overnight Delivery, ”a very Spencer Tracy-Katharine Hepburn romantic comedy,” costarring Paul Rudd (Clueless), in which she plays a stripper. ”I talked the filmmakers into it being her first night and she isn’t a very good stripper,” says Witherspoon, who, until winter term, is living in L.A. with her Chihuahua. She’s happy to report that the curse of her screen beaux has been lifted.