POLITE SEX by James Wilcox (HarperCollins: $19.95; 279 pp.) Hugh wants a woman who does not distract him with passion or lust, and so he marries Emily. She thinks their cozy, quiet intimacy is very nice, and she can’t understand why people get so intense about sex. In Hugh’s background are old money and a dominant mother. He struggles to define himself, no easy task because at the same time he tries to deny impulses that become obsessions. He fantasizes about lesbians and assumes that this probably means he’s not gay. Emily longs for a career in show business, but she fears this may embarrass Hugh and his mother. Emily’s best friend from Louisiana, the beautiful Clara, moves to New York, where they live, and before long she begins to act out Emily’s dream of stardom. Then Emily’s best male friend falls in love with Clara. As the years go by, Clara moves further into Emily’s life, and manages to steal most of it from her, without the least bit of malice. Along the way there are odd relationships, amusing moments, tenderness and charm. Sometimes you hate the things these people do to one another, but Wilcox convinces you that they mean well. His narrative is both charming and wry.