The underlying subject of many romantic comedies is chemistry, the mysterious rapport that draws people together despite whatever circumstances—being already married, having different sexual orientations—might be working against them. It’s a tough thing to simulate in movies because, well, that’s the nature of chemistry. So What If has a sizable gift in the casting of Daniel Radcliffe and Zoe Kazan, who either have terrific chemistry together or are able to fake it expertly.
In the opening scene, their characters, Wallace and Chantry, bond over refrigerator magnets at a party and he walks her home. She mentions her boyfriend at the usual moment for such things, and that becomes the major impediment to a quick resolution of this mutual-attraction club.