Tourism seems to liberalize many places. It must be all those liberals that go on tours and tell the locals how beautiful everything is, how lucky they are, and how much they want to live there. Before long, people start believing that stuff, and contrariness in the debates depresses the voters from their visitor-induced euphoria.
I gather Bend has a good amount of high technology (software, medical equipment manufacturing), which is the result of an economic diversification plan begun after the early 1980s, when they had a high unemployment rate. High tech firms and communities are frequently gay-friendly, to attract and hold on to the talented people they need to compete.