Can living in a crowded city make someone have a bad temper?

Ever since moving to a big city I have grown very impatient, angry & untolearble of people. What has happened to me? Crowds annoy the hell out of me, and I do not like going a lot of places here, because of all the people. This town used to be nice, but it has been overtaken by everyone. I get annoyed in traffic, in stores, restaurants, etc. What has happened to me? I used to be so layed back. I grew up on a quiet ranch in the country. My live in boyfriend doesn't understand why I don't like crowds like him. He loves being in the middle of a giant mob. I get annoyed.