How well do you know the hottest couples in country? There are the famous pairs like Tim McGraw and Faith Hill or Blake Shelton and Miranda Lambert, plus other stars whose plus-ones aren't in the music business, like Carrie Underwood and her hockey-player husband, Mike Fisher; or Luke Bryan and his college sweetheart, Caroline. For a fun blast from the past, check out your favorite country singers then and now, then get in the Valentine's Day spirit with a look at some of country music's most famous twosomes, plus fun facts you may not know about each pair.