What is the main conflict in An Abundance of Katherines by John Green?

In this novel, Colin Singleton is a prodigy and genius who just graduated from high school. Colin was just dumped by his nineteenth girlfriend in a row and all of his girlfriends have the name of Katherine - all spelled the same way. After Katherine the XIX dumps Colin, Colin's best friend, Hassan, comes to Colin's room to convince him that he needs to take a road trip to clear his mind and have an adventure. While it takes some convincing on Hassan's part, Colin finally agrees to go on the road trip.