"The Vow" (PG-13, 104 minutes). Rachel McAdams and Channing Tatum play a young Chicago couple who are happily married after four years when they're in an accident and he loses all her memories of being married to him--or even meeting him. She thinks she's still living at home with her parents (Sam Neill and Jessica Lange), and engaged to Jeremy (Scott Speedman). What's a girl to do? A well-behaved, tender-hearted date movie about impossibly nice people, but too sedate and safe.