In Clea DuVall’s “Happiest Season,” Kristen Stewart plays Abby, an art history Ph.D. student whose girlfriend, Harper (Mackenzie Davis), has invited her home for Christmas. Though she’s at first reluctant to go, Abby then decides she’ll actually propose to Harper, assuming that meeting the family goes well — but Harper tells Abby she hasn’t yet come out to her parents, and they both have to pretend to be straight. It’s a romcom with […]