Family Myths in Romantic Fiction

To give an idea of what they mean by "myths" here, I'm including a quote:

Myths Supporting the Traditional Family

Romantic fiction is about white heterosexual men and women whose often torturous courtship ends in marriage and who plan to have children rather sooner than later. Extramarital affairs, interracial couples, and homosexuality are unheard of; the rare instances of unwed parenthood stem from protagonists' prior life, before they met their current intended. By making the so-called traditional family pattern exclusive, this literary genre propagates a myth and distorts reality. (30-31)