Why is Sally crying at the end of the chapter?

Holden tells Sally his rather silly plan of running away and getting married. Sally tells him that the idea is foolish, for they are both practically children who would starve to death. She tells him that they will have a lot of time to do those things after college and marriage, but he claims that there wouldn't be "oodles" of places to go, and it would be entirely different from how she portrays it. He calls her a "royal pain in the ass," and Sally starts to cry. Holden feels somewhat guilty, and realizes that he doesn't even know where he got the idea about going to New England.