It was about chemistry but the fact is Jess was never emotional ready to commit to Rory... Sure he dated Shane but it was bc he had no "real" feelings for her and their relationship was purely physical
Richard: It costs a fortune to travel first class in Europe. We only do it every two years. Emily: In the fall. Richard: It’s just not in the budget this year. Lorelai: You don’t have to fly first class…cause there’s always coach, or business class is slightly less, there’s deals on the internet. Hmm. Pass the potatoes.