It takes a special kind of mainstream mush to waste Vince Vaughn, Kevin James, Winona Ryder, Jennifer Connelly and your money all at once. Screenwriter Allan Loeb and director Ron Howard have found the formula. They’ve made a movie so totally and resolutely mediocre that it’s almost impressive. While working up the courage to propose to his own girlfriend (Connelly), a man (Vaughn) discovers that the wife (Ryder) of his best pal (James) might be having an affair. What’s the man to do? Being Vaughn, he puts himself through the usual paces of wacky and garrulous humiliation. What should escalate as a series of comic or poignant or at least barely plausible complications instead just becomes a weird and wearisome degeneration. There’s some overheated talk about honesty, and then some overheated slapstick. It’s not wholly unfunny, just unnecessary. Also with Channing Tatum and Queen Latifah, neither of whom is allowed much dignity.