Love in the 21st century came with a few extra challenges, namely fast technological changes that would transform nearly all methods of wooing, flirting, and hooking up. Fortunately, this gave the biggest pop stars on the planet plenty more to sing about. The first half of the decade saw former teen heartthrobs Christina Aguilera and Justin Timberlake coming of age, navigating fresh love with smooth R&B beats and brilliant falsetto, while making room for openhearted acoustic mavericks, led by Coldplay and John Mayer, to paint their sweetest scenes in spectacular colors. By the second half, Taylor Swift was writing the book on modern love through intimate tales ribboned with exquisite detail, as Rihanna and Beyoncé gave us inspirational anthems that hit straight through pop, hip-hop, and the heart.