Scenario: Having sex seemed like a really good idea that night, but the next day … not so much.
Animal Advice: Honesty is the best policy.
Action: First figure out why you're feeling all wiggy about the sex. Was it bad? Was it too soon? Do you know that you don't really feel that way about him? Are you into someone else? Once you've assessed the root of your regret, you're going to need to let him know. That's the hard part. But the more honest you can be, the better. Oh, and the longer you put it off, the more nervous it will make you. So, just rip the bandaid off already and feel your freak out fade to black.