MRS. FLETCHER
HBO, 10:30 p.m. ET
Kathryn Hahn is really, really good as the empty-nest single mother in Tom Perrotta’s HBO adaptation of his own novel. At the end of last week’s premiere, she enrolled in an adult-education class, where one of the other students was a young man formerly bullied in school by her son. And as the final scene faded to the credits, she was flirting with the idea of flirting with that much younger man…