“Mrs. Fletcher” by Tom Perrotta might be “the sweetest and most charming (NYT)” story about bending sexual norms that you might ever read.  Eve Fletcher is a divorce leading an all-too-placid life.  To shake things up, she takes a night school class from a trans professor and develops an obsession erotica for the middle-aged.   Before long, her fantasies begin spilling over into real life.  Meanwhile, her lunk of a son, a college freshman, confronts the New Rules regarding consent. Perrotta “steers through this miry slough with sensitivity, skill and good-natured confidence.”