Call it romance porn—Rachel McAdams of “The Notebook” and Channing Tatum of “Dear John” are starring together in the movie “The Vow.” It doesn’t open until next February, but the first trailer came out today. The movie is about a totally in-love couple who are in a car accident when a truck smacks into them while they’re smooching. Rachel loses her memory, but Channing vows to stay with her and make her fall in love with him all over again. Strife ensues. And possibly a happy ending? But may I make a little observation here? This movie sounds an awful lot like a sad version of that Drew Barrymore and Adam Sandler flick “50 First Dates.” I happened to watch it last weekend—in it, Drew has a short-term memory retention problem after being in a car accident — thus Adam must make her fall in love with him every day. I’ll take the comedy version of this concept any day.