Photo: Lyvans Boolaky/Getty Images Crafting an enduring love triangle isn’t easy. But with The Summer I Turned Pretty , co-showrunner Jenny Han managed to pull it off, dividing viewers into camps in the grand tradition of fellow YA authors Stephenie Meyer and Suzanne Collins. Sure, it seemed increasingly apparent over the course of the third and final season that 21-year-old Belly Conklin (Lola Tung) would ultimately choose Conrad Fisher (Christopher Briney) over her fiancé, his younger brother,