Respect yourself.

If you say no, he should stop. If he doesn't stop, leave. Don't ever be uncomfortable saying no. Don't go against your morals to try to keep a guy. If you feel this is necessary, then either he's not a good man, or he is a good one but simply isn't a good match for you specifically (e. g. he is currently "playing the field" and is up front and honest about it, but you're looking for an exclusive relationship). Don't be uncomfortable saying yes, either. If you feel the time is right, believe in your worth and don't worry that you're "giving yourself away." You respect yourself and you're confident that he'll come back for more! A man who doesn't respect you in the morning never properly respected you to begin with, and a man who doesn't respect your wishes to wait is too impatient to make a good partner. Either way, find someone else.