Sometimes the most benign things can put a boy on edge...
Planning a Romantic Evening: Lighting candles or booking a hotel room for the night is sweet and all, but some guys wind up feeling a lot of pressure for it to be special, which can have a stress-inducing effect on them.
Taking a Class Together: If there's any chance your guy will wind up feeling inept (couple sushi-making lessons, anyone?), he may dread the activity instead of looking forward to it.
Winning Your Parents' Approval: He probably acts all debonair about it, but getting that thumbs-up from your parents is a biggie for him - especially your dad. Deep down, he's pretty concerned about whether they actually like him.
Hanging Out With Your Friends: It can be intimidating to be around a big group of women who are tight because he may worry that they're collectively sizing him up.
Pushing For Sex: Most of the time, erotic action will heal all of his woes. lf he's really stressed out, though, it'll be tough for him to get in the mood. And the harder you try, the worse he'll feel about not being up for it.