How to say no to sex?
You have the right to decide for yourself when you’re ready for sex, and to say “no” to sex at any time, with any person, for any reason (even if you’ve already had it). 

If you don’t want to have sex, speak up for yourself. If your bf/gf pressures you or threatens you to have sex or do sexual things against your will, it is a crime.
Here are some tips for saying “no”
•    You can also let them know that you really do like or love them, but you’re just not ready for sex. Remind them that it feels like they really care about you when they respect your feelings.