Nice guy Sandy (Art Garfunkel) and charming schemer Jonathan (Jack Nicholson) meet as college roommates in the late 1940s. Sandy woos and eventually marries the sweetly virginal Susan (Candice Bergen) without knowing that she had cheated on him with Jonathan. Years later, his marriage faltering, Sandy attempts to mimic Jonathan's promiscuous womanizing, while the misogynistic Jonathan finally tries his hand at monogamy with the gorgeous but emotionally needy Bobbie (Ann-Margret).