Society sorority princess rebels against parents and becomes an artsy chick who meets cute with a hipster doofus and falls in love, only to get amnesia in a car wreck, become a princess again, get divorced, go back to being an artsy chick again, meet cute with doofus again, blah, blah, happily ever after. So much for “The Vow” (2012). To be fair, the movie actually grows on you a little, like a mediocre restaurant you keep going back to because it’s reliably mediocre. Formula plots are formula plots for a reason. Channing Tatum plays the doofus for a reason.