This is a DATE, we're talking about right? Not a honeymoon? Come on, dates aren't about sex, they're about companionship. Nuff said!

Can be a pretty good reason to call off the date, if it's extreme. If it's a date (not a relationship), and he REALLY wants sex and you don't, if he doesn't back off, then yeah, it's a good idea to call it off. If it's a relationship, then hopefully you've known each other well enough to accept and make compromises. It can be difficult if one person wants it much more than the other, but hopefully things could be worked out.