You never have to abstain when using the Fertility Awareness Method. This is different than Natural Family Planning, which does require abstinence during the fertile phase. However, if you do have intercourse when you are potentially fertile, you must use a barrier method of contraception. The fertile phase will vary, but in practice this means that the average couple would have to use barriers about 8-10 days per cycle. The average cycle is 27-31 days, and thus for the typical couple, barriers (or abstinence) would be required for about 30% of the cycle.