what insight do we get into happy from the scene in the restaurant?

While Biff's failures and flaws have been a major preoccupation throughout the play, this segment demonstrates how detrimental Happy's character flaws can be. A compulsive womanizer, Happy tells blatant lies to the women that he meets, claiming that Biff is a professional athlete, then gets rid of his father in favor of seducing Miss Forsythe. In the final, most cruel move that Happy makes, he denies that Willy is his father, thus repudiating his father even more callously than Biff has done.