Gary Allan and Molly Martin, his fiancée of over two years, are officially married. Peoplereports that the couple spontaneously decided to tie the knot a the Sumner County mayor’s office in Gallatin, Tenn. last month, on Feb. 5. Only the officiant — who just so happened to be Mayor John C. Isbell himself — and a photographer were present to witness the ceremony. “Molly and I had been trying to find the right time and the right spot to get married, and we just decided the time was now. We just didn’t want to keep waiting,” Allan explains. “We may still do a bigger celebration later on, but for …