Bluegrass has a long history of artists taking on a sobriquet, a nickname, that helps identify them (or their status) both in and outside the bluegrass community. Bill Monroe was famously the Father of Bluegrass, and Jimmy Martin was variably the King or the Super King of Bluegrass. Rhonda Vincent has become the Queen of Bluegrass, or simply, The Queen.
The Sweethearts of Bluegrass is the tag applied to Darin & Brooke Aldridge, who do, indeed, appear to be quite fond of one another. Their show is squeaky clean and wholesome, full of uplifting and positive messages, and the tag just fits.
They stopped by our booth at World of Bluegrass last week for an interview, so you can see for yourself.