"Mamma Mia!" is so deeply strange. It is not a romantic comedy in the Nora Ephron sense. To meet Ephron's criteria, a pair of sparring lovers would need to separate, then reteam, then separate, then reteam. The End. "Mamma Mia!" is more like a domestic drama, like something by Eugene O'Neill. A young woman--Sophie--wants to discover who her father is. Being unwise and still sort of a teenager, she decides that the best route forward is to get married (though she does not want to get married). The wedding will allow her to invite a few "suspects" (possible fathers)--so that she can do some "sleuth" work and expand her circle of loved ones. Her fiance--bizarrely named "Sky"--is understandably upset when he uncovers this plot. But he still commits to getting married--for reasons unclear. The script seems to indicate that he is drawn to his girlfriend's "golden hair." Sophie is so confused and troubled, but her story...