Loads of celebrities struck up new relationships (and frowned-upon flings — ahem, Kristen Stewart) in 2012. Not all of these romances are surprising, but some certainly had us doing a double-click. Examples from both ends of the spectrum: We’re still squeeing over the Michelle Williams-Jason Segel pairing, and we can’t stop shaking our heads over Rihanna and Chris Brown’s rekindled thing (those two sure know how to avoid labels). Of 2012’s following celeb...