Trending on Billboard One of the longest-running themes in country music features a guy who’s left behind as his girlfriend heads off for the big city in search of a star-quality life. Explore See latest videos, charts and news That separation story played out in George Jones & Tammy Wynette’s “Southern California,” David Frizzell & Shelly West’s “You’re the Reason God Made Oklahoma,” Dan Seals’ “Everything That Glitters (Is Not Gold)” and Randy Travis’ remake of “It’s Just a Matter of Time.” More recently, Morgan Wallen threaded a version of that tale into “More Than My Hometown.” Newcomer Kevin Powers’ fresh take on the idea – “Move On,” featuring Shaboozey – casts it in a modern, folk-country package: brisk, catchy, mostly acoustic. But it still connects to country’s past as the woman in the text glitzes up her life by renting a high-rise in some unspecified West Coast town.…